Action type and physics

I have wondered how much energy is required to cycle a blowback-type semiauto action and how it affects ballistics. Has anyone ever measured the velocity of the same load out of similar barrels with one test gun being a semiauto and the other a bolt action?

There aren't too many straight blowback actions on full power rifle cartridges; there are a few roller-delayed blowback types, though. The energy required to cycle them depends directly on the recoil spring strength of the bolt. The stronger the spring, the more energy it takes to compress it. The idea is that the spring must be strong enough, in tandem with the bolt being massive enough, to delay the bolt from coming out of battery until chamber pressure has dropped to a safe level.

There is likely a (very) small effect on muzzle velocity in a blowback vs bolt action design, but it's probably no more parasitic than a gas operated action. The recoil force is just being harnessed directly by the action instead of it all transferring straight to the shooter's shoulder.

I was thinking more in terms of 22LR but then it got me thinking about pistol cartridges...obviously there are no bolt action pistols but I was thinking the same physics would apply.

The recoil force is just being harnessed directly by the action instead of it all transferring straight to the shooter's shoulder.
This makes sense. Thanks.

Just conjecture, but I would expect other characteristics of a particular gun (rifling depth, number of lands, barrel twist, minor and major bore diameter, bore fouling, etc.) to make a bigger difference in robbing energy.

After all, if you can rack the action of a blowback 22 rimfire using just two fingers then it certainly doesn't take much energy away from the system.

obviously there are no bolt action pistols but I was thinking the same physics would apply.


Actually, the Remington XP-100, Savage and Weatherby were all bolt action pistols

I was thinking more in terms of 22LR but then it got me thinking about pistol cartridges...obviously there are no bolt action pistols but I was thinking the same physics would apply.

There are a few bolt action pistols out there, but most are chambered in full power rifle rounds. Bolt action doesn't doesn't lend itself to use for pistols with pistol cartridges. There ARE a few bolt action rifles chambered for pistol cartridges though, such as the De Lisle Carbine.

As for .22lr, a bolt action vs blowback autoloader, variances in barrel length and rifling twist ratio will probably make more of a difference than the action type in terms of muzzle velocity. Indeed, standard deviation between individual cartridges is probably larger than any velocity differences you'd see in two different actions with the same barrel length.

The bolt action is potentially more accurate, however, because the action is locked during the time the bullet is travelling down the barrel (and thus there is little to no reciprocating mass which can throw off your aim). This difference is VERY small, however, and you'd need a pretty tricked out set of rifles and a world-class shooter to measure it.

I seem to remember reading about a 30/06 blowback rifle designed and submitted to the trials by Col. Thompson when the Army was looking for a semi-auto service rifle. (The trials that ended up with the Garand being selected.)
Anyway, apparently the ejection was a bit daunting. It was reported that it was sticking empty cases into an oak door off to the side of the test area.:eek:

I think he was trying to use the Blish lock that didn't work very well in the submachine gun either.

Blowback action: I've wondered how far the casing moves before the bullet is out of the barrel. Anyone know?

A key part of the design is to slow the movement of the casing with springs, and with the mass of the slide.

Blowback action: I've wondered how far the casing moves before the bullet is out of the barrel. Anyone know?

I have seen slow-motion video of a 1911 style pistol being fired in a fixed rest. The bullet is clear of the barrel (but still visible in the frame - only a few inches away) before there is any appreciable rearward movement of the slide.

Yes...in any of these, far as I know, the Bullet has left the Barrel before the Action is in motion...so, there's no loss of FPS...

The action DOES begin to move as soon as the bullet begins to move (simple physics). But the action moves less than a millimeter before the bullet leaves the barrel.

Regardless of what type of action, or what caliber you talk about.

The bullet has to be out of the barrel and bore pressure dropped to near atmosperic before extraction can take place.

If the action opened before bore pressure had dropped off and the case relaxed it's grip on the chamber, the gun would blow up in your face.

rc

I have seen slow-motion video of a 1911 style pistol being fired in a fixed rest.

A 1911 fires from a locked breach it isn't a blow back action.

Thank You rcmodel....

If one of you would like to get a blow back 22 and a Thompson Center break action pistol...it would be interesting.

I once did a test, using a Ciener Conversion Kit on an M1911. I fired .22 ammo from the same lot, half with the gun as issue, half with two 1-lb weights clamped to the slide. There was no significant difference in muzzle velocity.

get a blow back 22 and a Thompson Center
Hey! Anyone with a cronograph can test it out of the same gun.
Which is the only way to test it and get meaningful results.
No big trick to hold the bolt shut on a .22RF.

Shoot a string semi-auto and another string holding the action closed with your thumb on the operating handle or slide.

I'd bet my booties the SD of the ammo used will be more then the differance between locked & not locked.

rc

I do not know for sure, but I think trying to hold the bolt or slide shut with one's thumb, finger, or any other body part might not be the best thing to do. Having done it a couple of times many years ago finally "cured" me of it!

If anyone has a Springfield 87a or one of the Savage/Stevens version that would probably work best for testing this out since you can fire it in semi-auto then lock the action closed and shoot it like a bolt action.

A 1911 fires from a locked breach it isn't a blow back action.

Yes, it is. It's a "delayed blowback," - but it certainly is a blowback action.

The action DOES begin to move as soon as the bullet begins to move (simple physics). But the action moves less than a millimeter before the bullet leaves the barrel.

No, the physics are more complicated than that. From video evidence, it certainly does not move even a millimeter before the bullet is free from the barrel. Consider:

1) The interaction of the slide/cartridge base is, for the period the cartridge is trapped in the chamber, an "inelastic collision" in classical physics.

2) It's not a "pure" inelastic collision - there is tension besides the mass of the slide in the form of pressure from the recoil spring.

3) once the cartridge is allowed to ricochet off the ejector, you now have an elastic collision, and a different set of equations to apply.

3) peak pressure is not reached with the cartridge still in the case, it comes later, when the bullet is travelling already.

There is no single "simple physics" equation to deal with this complicated interaction, you have to use several and then integrate them. It is entirely within the physics of the situation that the slide in a given gun does not reach a point where its inertia and that of the spring are sufficiently overcome to start the motion with the bullet free of the barrel.

From video evidence, it certainly does not move even a millimeter before the bullet is free from the barrel.

Sorry, Oro. It certainly does move before the bullet exits. It's Newton's 3rd Law at its most basic.

In order for an action/reaction event to occur, there must be a vectored force between two objects. If the bullet is gone before the slide moves, half the equation...the "action" half...is missing.

No action = no reaction.

For the record...The 1911 is almost a delayed blowback. The only thing that keeps it from being a true blowback is the fact that the slide doesn't move independently of the barrel...and even straight blowbacks operate from recoil forces.

Let me go find a link to a video that'll let you see it happen, and I'll be right back.

Try this one. It'll take a few seconds to load.

http://smg.photobucket.com/albums/v323/sv1cec/videos/?action=view&current=hispeedteaser_mid_w-1.flv


There are several guns firing in slow motion. The last 1911 is the one to watch closely. It's a stop-action clip of the gun firing. The first thing you'll notice is a tiny bit of slide movement rearward...then a light wisp of blowby gasses...and the slide moving. Then, you see the bullet nose start to peek out of the muzzle...and the slide is still moving. Finally, the bullet exits, and the fireball follows.

The slide moves and pulls the barrel backward with it. At about 1/10th inch, the linkdown phase begins. At that point, or just before the linkdown phase starts...the bullet exits.

Watch closely.

Interesting...what?

PS

Kuhnhausen's "Balanced Thrust Vector" description is utterly wrong.

Wow, thanks for the vid, Mr. Tuner. I always wondered what was causing that little thumbnail-ish ding on my brass. Now I knowhttp://i274.photobucket.com/albums/jj241/proud2deviate/thumbsup.gif

How 'bout the bouncin' bolt on that AR15?

I was reminded of a marble on a cake plate (don't tell mom!)

Sorry, Oro. It certainly does move before the bullet exits.

I certainly can't tell from that video when the bullet exits and any perceptible slide recoil happens. I have seen this video, it was what I was referring to above. It certainly makes it clear no slide recoil is happening before the bullet exits the barrel:

http://www.youtube.com/watch?v=tiHTZzE1NdA&feature=related

It is certainly possible for one item in a collision to have a major vector change before there's perceptible movement in the other party to the collision. It's very basic and involves inertia and momentum. If you compare the mass of the slide to that of the projectile, as well as the added force of the spring holding it in place. Sometimes I find it easy to understand and explain these concepts with extreme examples:

Imagine throwing a marble from a dock at a cruise ship passing by. Did you see the marble bounce and change direction? Did you see the cruise ship shudder or recoil? The lack of apparent change in the ship doesn't mean there wasn't an interaction between them.

Another example is a battleship firing a broadside. Even firing all guns at once, a WWII era battleship suffers no displacement laterally from it. Does that mean no work was done on the ship by the massive energy absorbed by it in firing 20,000 lbs of projectiles at basically high-powered rifle velocities (I believe around 3000fps)?

Those are extreme examples, but they help make it clear that you can have a collision or "action/reaction" where the vector change on one body is dramatically quicker than upon the other body.

I certainly can't tell from that video when the bullet exits and any perceptible slide recoil happens.

Brother...If ya can't see it, it's because you refuse to see it. In the very last one...before the snub revolver...slide movement is clearly seen even before the initial blowby gasses escape.

If the bullet is gone before the slide moves, the slide won't move...at least not very much. While the exiting gasses and burned particulate have mass...it's not much mass. It's equal to the mass of the unburned powder charge. In the typical .45 ACP cartridge...that's about 5 grains. Even at a theoretical 4,000 fps exit velocity...which I think is pretty fanciful...that would amount to about 1/5th the recoil impulse generated by a standard velocity .22 Short. Not nearly enough to move the slide with the force and at the speeds that occur during the cycle.

The theories that you offered are impressive...and I'm not being facetious when I say that. I'd have accepted it if I didn't already know better, but you're making this thing way more complicated than it is. Recoil...and recoil operated...is nothing more (complex) than Newton's 3rd Law.

If the forces imposed in an action/reaction system are great enough to set both sides of the system in motion...they'll both move at the same instant. They don't have a choice.

Very interesting...

1911-wise...

The Breech/Slide, and Barrel, moving as-one, begin to move, prior to the Bullet leaving the Barrel.

The Breech/Slide, and Barrel, moving as-one,

Yep. The bullet is driven forward by the force resulting from the expanding gas. The slide is driven rearward by the same force...and because the upper barrel lugs are meshed with the slide's...the slide pulls the barrel backward with it. This is the locked part of "Locked Breech."

And...because the bullet's passage thru the barrel is exerting a strong forward drag on the barrel...the slide is resisted by that forward drag on the barrel. Of all the mechanisms that are delaying the slide in this...essentially a delayed blowback function...the bullet's influence is the major player. It eclipses the effects of all the others combined.

Other delaying mechanisms:

Slide mass.
Barrel mass...for a brief instant.
Recoil spring.
Mainspring.
Slide/frame friction.
Slide/hammer friction.

Another example is a battleship firing a broadside. Even firing all guns at once, a WWII era battleship suffers no displacement laterally from it.

Yes it does, just not noticeably so.


And to take your marble example further, if you hit the cruise ship with your marble, the cruise ship DOES get pushed back; just not in any meaningful way or distance.



Of all the mechanisms that are delaying the slide in this...essentially a delayed blowback function...the bullet's influence is the major player. It eclipses the effects of all the others combined.

Slide mass is THE most important factor in delaying blowback until safe chamber pressures are achieved, at least in a straight-blowback pistol such as a Hi-Point. This is why their guns are so ugly, because the slide has to be huge and massive to retard blowback. The 1911 locked breech design retards cycling enough that the slide can be made significantly lighter while still delaying the action from going out of battery before chamber pressures reach atmospheric level.

Another example is a battleship firing a broadside. Even firing all guns at once, a WWII era battleship suffers no displacement laterally from it.


Sorry again, Oro. Not a valid argument.

It's not a prerequisite for both sides of the action/reaction system to move. If one side doesn't move, it's because the force wasn't of a sufficient magnitude to overcome its inertial and frictional resistance. Build a .308 rifle that weighs 200 pounds, and you can fire it without feeling a bit of recoil.

Go push on a house. You move, but the house doesn't...because you couldn't generate enough force to move it and because your resistance...either your inertial mass or by planting your feet...wasn't sufficient to utilize the force even if you could. That doesn't mean that the house didn't feel an accelerative force. It felt one. It just wasn't enough.

Back to the battleship with all guns firing. The reason that it didn't displace was because the combined recoil impulse and momentum from all projectiles and their velocities combined weren't of a great enough magnitude to overcome the ship's inertial mass and set it into motion. The ship "felt" a kick. It just wasn't enough of a kick to make it move. Lighten the ship enough, or make the projectiles heavy enough at the same velocities...or increase their velocities to a level that will generate sufficient momentum...and he ship will move.

Force forward equals force backward. Whatever force is imposed on one side of the system, an equal level of of force will be imposed on the other side. This is the heart of Newton's 3rd Law.

Again...

If the force applied is great enough to set both sides into motion...they'll both move at the same instant. They don't have a choice.

1911Tuner, in regards to the pushing of the house...

This is where elasticity comes into play. Regardless of the construction of the house, it will not move in one solid piece (unless it was built from a solid steel billet :D). The point you're pushing on, will move far more than the rest of the house. The rest of the house will feel the tension on it from that point, but will generally not move because it is anchored by its foundation, which is anchored by the earth. Since you are ostensibly also on the ground, you're effectively pushing against yourself. This is why bulldozers don't move houses, so much as destroy them in place.

Now, if you took a rocket motor, and strapped it to the side of your house, and lit it, the rocket motor would not only be pushing the house, it would also be pushing the entire earth. Due to the earth's high mass and inertia, the rocket will not appreciably change the earth's rotational rate. But it will change it, to some infinitesimal, probably immeasurable degree.

I understand elasticity, Gen'l. Tryin' to keep this question from devolving into an argument over semantics. I know the house moves. It just doesn't move enough for the human eye to detect it.

On the battleship thing again...if I may.

Assuming that all 9 of the ship's 16-inch guns fire at exactly the same instant...and that each projectile weighs 2,000 pounds. That's 18 tons of mass being accelerated. The USS Missouri weighs 45,000 tons. Without even considering the resistance offered by the water that the ship is sitting in...18 tons is a small fraction of the ship's mass. Expecting the guns firing to move the ship any appreciable amount is rather like trying to stop a train with a baseball bat.

Ain't gonna happ'n Cap'n.

And, no...Firing the ship's 5-inch guns with the main guns ain't gonna add enough to make a difference, either..

Hell, each turret weighs 1,700 tons...

Brother...If ya can't see it, it's because you refuse to see it.

Er, I'm looking straight at it and I can't see it:

http://www.youtube.com/watch?v=tiHTZzE1NdA&feature=related

It's possible there are different load levels being photographed; it's possible they are guns with different springs. I also think in the video above the gun is not in a fixed rest; because I think I see rearward displacement of the whole assembly (gun) before and rearward movement of the slide begins to take place. But since neither of us actually performed the tests and can swear and affirm to all the test parameters in each, it's best to just say the visual evidence is what it is and not try to defend some unknown persons undocumented work.

But classical physics certainly does NOT preclude getting a bullet out of a barrel before a blowback feed system starts to work.

Sorry again, Oro. Not a valid argument.

It's not a prerequisite for both sides of the action/reaction system to move.

I think you are agreeing by disagreeing? That was exactly my point and what my examples were trying to point out. But critically as the spectrum of possible and plausible examples allow, one side of the equation can move FASTER than the other, based on relative mass and inertia. That was precisely my point and what the cruise ship/battle ship examples were trying to illustrate.

18 tons is a small fraction of the ship's mass. Expecting the guns firing to move the ship any appreciable amount is rather like trying to stop a train with a baseball bat.

and 185 (or 200, or 230) grains is a small fraction of a slide and barrel assembly's total weight - 3.5%, to be exact (using 200 grains vs. a 19.5 oz slide). This is still relatively less than the weight of a South Dakota-class battleship's main-gun broadside, but still, the point is the same. Factor in how the impulse is delivered over time, and it's exactly the same point.

Slide mass is THE most important factor in delaying blowback until safe chamber pressures are achieved,

Geoneral Geoff, I agree with most your reasoning, but in this case make a test: it's spring tension. Place a slide on an auto without the recoil spring. Try to push it back with your finger. Then assemble it correctly with the spring in place and try it with your finger. Now make a "finger tip gauge" guess about which offers more relative resistance. It's the spring.

You can run the equations of elastic/inelastic equations with the slide and the bullet, but without factoring in the spring tension you are wasting your time - that's what my first post was trying to explain. This case is neither; it's a combination of the two types of "collisions" as classical physics calls them.

It's entirely possible, given the relative inertia of the slide and tension of the spring, to get a bullet out of a blowback firearm before the impulse momentum of the cartridge's recoil overcomes the inertia of the slide and spring and displaces them both backward. It's theoretically possible, it's mathematically possible, and there is photographic evidence to show it.

Geoneral Geoff, I agree with most your reasoning, but in this case make a test: it's spring tension. Place a slide on an auto without the recoil spring. Try to push it back with your finger. Then assemble it correctly and try it with your finger. Now make a "finger tip gauge" guess about which offers more resistance. It's the spring.

You can run the equations of elastic/inelastic equations with the slide and the bullet, but without factoring in the spring tension you are wasting your time - that's what my first post was trying to explain. This case is neither; it's a combination of the two types of "collisions" as classical physics calls them.

The finger tip gauge isn't really a good indicator of the forces at work here; a better indicator would be using a rubber mallet, and tapping the front of the slide. Pushing with your finger provides low but steady force (which is all that's needed to move a slide without a spring). Tapping with the mallet provides high but momentary force, just like firing a round (which will easily overcome the spring force, but the momentum will slow down the slide movement just enough).

The spring is not there to retard the action from going out of battery; it is there to return the action to battery. In order for the spring to provide enough resistance to sufficiently retard the action on its own (or mostly on its own), it would have to be so strong that the blowback force couldn't push the slide all the way to the rear.

As is evident from the video footage, the bullet leaves the muzzle long before the slide moves very far. After the point where the bullet leaves the muzzle, the force being exerted by blowback is zero. Why does the slide keep moving back? Inertia. The blowback force has already acted on the slide, and has started pushing it back. The ONLY thing pushing it back after the bullet exits the barrel is inertia. That is what overcomes the spring strength, sheer inertial force; not blowback. If the spring strength alone could retard the blowback force, the slide wouldn't budge at all upon firing.

You don't see it because you refuse to accept what you're seeing. Everybody else sees it.

Watch closer. Pay attention to the end of the slide in relation to the left edge of the photo. Watch it get closer before the bullet exits.

The slide's spring tunnel moves closer to the dust cover before the blowby gasses appear. Watch it close, now...and accept what your eyes are telling you.

Even in the first video of the compensated pistol. The slide moves just a tick before the fireball appears in the ports. Because the fireball follows the bullet...it only stands to reason that by the time you see the fire, the bullet is well ahead of it, and the slide is well on its way.

And no...I'm not agreeing by disagreeing. One more time...If the force within the system is large enough to overcome the object's inertial and frictional resistance to acceleration...both objects will move at the same instant. They have to.

On the other hand, if one side can be moved by the applied force, and the other can't...then only one side will move. Go push on a house, and then go push on an empty refirgerator box. See the difference?

When you push...you immediately get pushed. If the bullet is gone before the slide moves, there's nothing for the force to push off of...no resistance to work the reaction side. Like frog-kicking in mid-air. You ain't gonna move far.

Hell, each turret weighs 1,700 tons...


Now that you mention it...If I'm not mistaken, the ship's weight...displacement...is figured before anything else is added to the structure except the engines and props. Correct me if I'm wrong.

You don't see it because you refuse to accept what you're seeing. Everybody else sees it.

http://www.youtube.com/watch?v=tiHTZzE1NdA&feature=related

Feel free to dissect this video, but where is the rearward displacement? I just don't see it or hear anyone else saying they see it...

If I'm not mistaken, the ship's weight...displacement...is figured before anything else is added to the structure, except the engines and props. Correct me if I'm wrong.

Nautical "displacement" is figured a number of different ways - both dry, loaded (typical load), and "full load" (design limit), so unless it's footnoted or qualified, you can't know what is meant. It's very directly equivalent to load ratings on a truck - the vehicle weight, registered weight, gross weight, etc. A typical WWII US battleship (the "fighting" ones - the South Dakota/North Carolina class) would weigh around (estimated) 45,000 tons fully loaded with fuel/munitions/stores/crew.

Oro, look at the bottom of the video, at the guide rod. Notice how it is NOT moving, but the barrel and slide are.



edit; also, that doesn't really look like a 1911 to me. The principles are the same though; judging from the barrel and slide moving as one initially, it looks like whatever the pistol is, it uses the same locked breech design as a 1911.

Here ya go, Oro. This is a very old ordnance x-ray picture. Look at the bullet...and then look at the position of the barrel link. The link doesn't get in that position until the barrel has moved a 10th of an inch. Here, the barrel is almost at the beginning of the linkdown point.

Look at the lugs while you're at it. The slide is pulling on the barrel.

Yes. It's firing. You can see the outline of the bones in a human hand if you look carefully.

http://i40.photobucket.com/albums/e243/1911Tuner/Gun20Fired.jpg

Heh, you can see some denser parts of the bones in the shooter's hand. Awesome picture, 1911Tuner.

Geoff, you can even see the gasses and smoke in the barrel behind the bullet. Look at the difference in coloration of the barrel behind the bullet and in front of it.

If memory serves me...that picture dates back to 1916. Probably to settle an argument over whether the slide moves before the bullet exits. heh.

Also, going back to the battleship tangent: A technical essay answering: Do Battleships move sideways when they fire? (http://www.navweaps.com/index_tech/tech-022.htm)

As an interesting side note, the Mark 7 50 caliber 16" naval guns used on the Iowa had NUCLEAR shells available, called the Mark 23; using a W23 warhead, the nominal yield was 15-20 kilotons. How crazy is that?? Makes that 280mm (11") nuclear artillery cannon look like a toy...

Gen'rul...That was excellent! I didn't even factor in the guns' elevation. I assumed horizontal...and even that wouldn't move the ship laterally very far in water. I'd venture a guess that the distance would be measured in fractions of an inch.

Also interesting that an Iowa class ship is 57,000 long tons...seaworthy.

At any rate...I'm havin' me a large time with this one.

Carry on!

Do you guys even know what blowback means??? You're getting it confused with recoil operated. A 1911 is a locked breach gun. It can't be locked breach AND blowback. Haven't you ever wondered why the barrel tilts on a 1911? That's the locking mechanism.

The locking breech mechanism is just an interim step to help retard the recoil operation. There's no reason why it couldn't technically be considered "delayed blowback."

Here ya go, Oro. This is a very old ordnance x-ray picture.

That is the most interesting and unique picture of a 1911 I have ever seen. I've collected a few in the last few years but that takes the cake. I have some professional training in radiology (albeit with a very different subject) so let me state what I see :

1) I see the lower lug is indeed off the link.
2) I see what I *think* is vertical displacement of the slide from the barrel because of recoil - it is evident both at the bushing and in the lug spaces.
3) I see rearward displacement of the slide relative to the barrel, not so much apparent at the muzzle but clearly apparent at the hood/breech interface.
4) I don't see any evidence of rearward displacement at the muzzle (I should), but I clearly see it internally and at the barrel hood as noted above.
5) The shooter has an incident of hyper-mineralization of the distal bone of the second phalanges. More tests are in order.

Since that's a "true" 1911 based on the radiograph, I'm guessing this is circa 1910-1920, meaning 230gr. and 825fps, 16lb spring. Given those parameters, the bullet is not out of the barrel and the slide is recoiling. Case proved. And with style.

I will note I hedged my statement above about recoil spring weights and bullet weights. This clearly shows that with standard rounds and springs, you will get slide movement before the bullet exits the barrel. (But it's fun to talk about battleships, isn't it? ;)

And by the way - the North Carolina or South Dakota class were more than a match for the Yamato and Musashi - looks like you all googled up Langdorff or some of the other experts' work on large caliber ballistics. If you are interested in it, pm me and I'll send some more interesting links and historical work.

In case you think I'm being non-topical, the wide-spread use of STS steel during WWII for naval vessels is directly linked to the major advancements in firearms that happened in the '50s and '60s. US battleships of WWII and the S&W Model 60 in your pocket are directly linked.

Seriously though, that guy needs to see his doctor. ;)

The locking breech mechanism is just an interim step to help retard the recoil operation. There's no reason why it couldn't technically be considered "delayed blowback."

+1 - that is how I've always read it to be defined. "Blowback" means the cartridge recoils against the breech to actuate cycling. It's pretty simple - the cartridge is "blown back" and makes the gun work. Delayed, rotated, direct, toggle, - all still blowback.

If you want to get REALLY pure on definition, technically all blowback mechanisms are gas operated, with the empty cartridge case still in the chamber acting as a gas piston pushing directly against the bolt face.. :)

If you want to get REALLY pure on definition, technically all blowback mechanisms are gas operated, with the empty cartridge case still in the chamber acting as a gas piston pushing directly against the bolt face..

Dammit, I wish I'd thought of that. You are clever, aren't you? ;)

That's so frackin' obvious - the cartridge is indeed a gas piston. You get the "Mr. Watson" award for the year.

You guys keep confusing recoil operated with blowback. THEY AREN'T THE SAME. Blowback guns do not fire from a locked breech period. And no the barrel on a 1911 doesn't unlock till the bullet is gone.

Why does the locked breech have to change the very definition of the action? The movement of the bolt face being pushed rearward is STILL what causes the breech to unlock, and the inertia from the bolt (locked with the barrel at the time) is STILL what causes the slide to move rearward after the breech is unlocked; in effect, this means it's just delayed. "Recoil-operated" is adding a superfluous category to an otherwise fairly simple concept.

We're not at all confused jerkface. Do you understand that they both operate from the same thing? Recoil forces. Force forward equals force backward. The force that drives the bullet forward also drives the breechblock backward.

"Recoil-operated" is adding a superfluous category to an otherwise fairly simple concept.


Exactly.

Geoff...Methinks that jerkface thinks he's talkin' to a buncha beginners here. ;)

Jerkface...We're well aware of how the locked breech/recoil operated pistol functions.
I got that part either figured out or explained to me in or around 1962, give or take.

We know that the barrel not only doesn't unlock until the bullet is gone...but that it can't unlock until after the bullet is gone.

We understand that the gun isn't actually locked until it fires...that the "lock" occurs under pressure, because of the bullet exerting a forward drag on the barrel while the opposite force drives the slide backward, and the lugs are engaged under a shearing stress.

We understand that the slide and barrel only move a short distance when the bullet exits.
About 1/10th inch, as it were.

We also understand...and I think that this is the part that you're a little shy of...is that other than the mechanism used to delay the opening of the breech...there is really no difference in the two. They both work based on Newton's 3rd Law of action and reaction.

So...The recoil operated pistol is a delayed blowback, and the blowback...whether straight or delayed...is recoil operated. The two are same-same.

1911 Tuner -

I would like to know where you found that radiograph of the 1911 in recoil. That's interesting on multiple levels and worth using as a teaching point, both for 1911's and radiography. I don't doubt it; I just would like to cite it.

1911's are not delayed blowback they are locked breach. CZ-52's are delayed blowback. Hi-Points are blowback.

Quote:
Another example is a battleship firing a broadside. Even firing all guns at once, a WWII era battleship suffers no displacement laterally from it.




1911Tuner's response:

Sorry again, Oro. Not a valid argument.




...

I knew there was a reason I kept these shots in my photo file:

Observe the bow and the water line: With a full broadside

Oops.. wrong pic.. ;) But now that I have your attention:

http://i217.photobucket.com/albums/cc306/Lonestar49/Micro_bikini_30.jpg

Here's the right ones:

http://i217.photobucket.com/albums/cc306/Lonestar49/Iowafullbroadside.jpg


http://i217.photobucket.com/albums/cc306/Lonestar49/battleship-blast.jpg


Ls

Oro:

5) The shooter has an incident of hyper-Oromineralization of the distal bone of the second phalanges. More tests are in order.

The increased density that you are referring is not the distal phalanx of the “second phalanges”.
Fingers are described as digits and phalanges are the three bones (proximal, middle and distal) of a digit and the distal phalanx would never be described as the second of the phalanges. Besides, all the distal phalanges would be out of view because they are obstructed by the pistol.

If you were erroneously referring to the finger with the increased density under the trigger guard as the second finger that would be and error too. The thumb is counted as the first finger, the trigger finger as the second finger and the one under the trigger guard as the third finger.

Oro:

More tests are in order.

This would not qualify as a diagnostic x-ray because there is not enough detail. The increased density that you are observing may simply caused by the superimposition of the proximal and middle phalanges and possibly complicated by the focal film distance or even scatter radiation if an appropriate grid was not used.

This poor for diagnosis x-ay does not exclude the possibility of pathology. However, in absence of any clinical information such as edema, inflamation, complaints of pain, reduced range of motion, patient history, etc. further tests would probably not be in order. However, continued vigilance is a safe route to take. If you are worried about a malpractice suit and really don’t care about unnecessary invasive tests and their attendant high costs, then by all means go ahead and order more tests. Damned if you do and damned if you don’t IMO.

If this x-ray was take in 1916, it would seem that the shooter wouldn’t need or be available for more testing anyway! :D

Do you think that since you made an error looking at that x-ray there is a possibility you may have made an error in looking at those videos?

Physics was a required course for my undergrad degree and I’ll have to admit that it was a looong time ago and I don’t have any of my texts to corroborate your explanation of collisions.

If memory serves, and it may not, all collisions were classified as either elastic or plastic and I don’t recall that a plastic (inelastic by your description?) could become an elastic collision. Plastic and elastic collisions were defined at their outset and I’m unaware that either can change in a time continuum. I would like to see a reference to update my understanding of those principles.

If your physics are in error, do you think there may be a possibility that you may have made an error in your explanations?

We understand that the slide and barrel only move a short distance when the bullet exits.
About 1/10th inch, as it were.


Another pic added to the fray.

I just learned a whole lot about 1911's... my brain is now fried... some cool ass pictures too...

Oro..I've had that thing for so long, I don't remember. Only that it was an ordnance picture...likely taken at Colt. You might try there.

Jerkface...I'd suggest that you think on it a bit longer...but I'll try one more time, just for the sake of broadening your understanding.

The only differences between the straight blowback and the recoil operated pistol is the slide on the latter doesn't move independently of the barrel...and the mechanism used to delay the breech opening.

That's it. That's the only difference.

There are many mechanisms that can be used to delay the breech opening in a delayed blowback. For instance...Heckler and Koch's G-3/91 rifles use a pair of spring-loaded rollers that cam into mating recesses in the receiver. Still others use gas, cams, toggles, or even springs to effect the delay.

The blowback...delayed blowback...and the recoil operated pistol ALL function by means of force forward/force backward, action and reaction...or in other words...recoil. The locked breech design uses the bullet itself as its most prominent delaying mechanism.

Like General Goeff pointed out to you so elegantly. (Paraphrased) "Recoil Operated" is a term that muddies up the water and lends unnecesary complication to what is a very simple operating principle.

Several years ago, one of the top gunsmithing schools in the world stopped referring to the 1911, the P-08 Luger, and others as recoil operated...and started describing them as delayed blowback in operation...because that's what they are.

Like this:

Bullet<---{BANG}--->slide

The fact that the barrel goes along for the ride for a short distance is incidental.

Hud...Good picture. Wonder how long it took to time that just right. :D

Haven't you ever wondered why the barrel tilts on a 1911? That's the locking mechanism.

yes, Jerkface. We understand why the barrel tilts. Do you?

The barrel tilts in order to let the upper lugs engage the mating lug recesses in the slide. It's not the locking mechanism. It's necesary to get the lugs engaged.

For the record. The barrel engages with the slide vertically. The breech locks horizontally...when the gun fires.

If the M1911, P08, etc. are "delayed blowback", what are the Remington M51, the Italian Glisenti and the several models of Savage auto-loaders? (or are we just going to lump them all together?)
Along the same lines what about the Frommer Stop and the Schwarzlose?
There was also a rifle designed by Pedersen that unlocked the bolt based on primer set-back.:evil:

IIRC, the Gilsenti is technically a delayed blowback, but not a locked breech in the pure sense. Kinda fuzzy, but it employed a mechanism that had a lever that held a separate breechblock against the barrel until the pressures had dropped enough for safe opening. Obturator? Seems like that's the term.

Lord...I haven't seen one of those ugly things in 35 years. Reminded me of the Nambu.

Here's a short description of the M51 Remington. A very pretty pistol to my eyes, but I've never had my hands in one.

The layout of the Remington 51 is similar to the Walther PPK pistol in the use of a stationary barrel and recoil spring surrounding the barrel. However, the unique feature is the use of a locking breech block within the slide. When the pistol is in battery, the breech block rests slightly forward of the locking shoulder in the frame. When the cartridge is fired, the bolt and slide move together a short distance rearward powered by the energy of the cartridge as in a standard blowback system. When the breech block contacts the locking shoulder, it stops, locking the breech.

The Schwarzlose is a "blow forward" so there is no way it can be called a "blow-back".:p:neener::evil:

The Frommer Stop is the only example of a Long Recoil action pistol I've ever seen. (I believe the British Mars may have used this system also.)
The barrel and breech stay locked together through the entire rearward function. Once they both reach the back of travel, they are unlocked and the barrel returns to battery, ejecting the case on the way. When the barrel has returned forward, the breech (slide, bolt) is released and travels forward , picking up and chambering a fresh cartridge. A very interest piece of mechanics.
To me the mystifying part is just why Frommer decided to use this complicated system on a .32 Auto.:scrutiny:

The Schwarzlose is a "blow forward"

Oh, yeah! That thing! Barrel gets dragged forward by the bullet and takes the breechblock with it. I remember reading about it a few years back. Interesting design.

Anyway...Back on topic.

Everybody understand that the slide moves while the bullet is in transit, and that the bullet is the main delaying factor in the locked breech pistol?

Excellent!

On to straight blowback.

Well...The slide gets pushed back by the same force that pushes the bullet with no mechanical connection between slide and barrel. The necessary delay comes from slide mass and recoil/action spring resistance.

Simple, what?

Jerkface! Got it all sorted out?

I'll recap:

Regardless of whether it's a straight blowback...a delayed blowback...or a recoil operated weapon...they all function from recoil forces imposed on the breechblock. Or...as Geoff noted...gas/piston operated.

The Colt-Browning tilt-barrel design engages vertically and locks horizontally.

I thought that in a blowback (delayed or otherwise) operated gun, the main force that cycles the action is the gas pressure pushing back on the cartridge. I don't see how a locked breech gun like the 1911 can work that way at all, considering that the barrel doesn't unlock from the slide until after the bullet has left the barrel and the pressure inside the barrel has vented out the muzzle.

I thought that in a blowback (delayed or otherwise) operated gun, the main force that cycles the action is the gas pressure pushing back on the cartridge.

It's the only force. it's also the only force that drives the slide rearward in the locked breech pistol. It's the only force available in either one.

I don't see how a locked breech gun like the 1911 can work that way at all, considering that the barrel doesn't unlock from the slide until after the bullet has left the barrel and the pressure inside the barrel has vented out the muzzle.

The fact that the barrel doesn't unlock/disengage from the slide until the bullet exits doesn't have anything to do with what drives the slide. The same mechanism that drives it rearward in the blowback drives the slide in the locked breech pistol.

A brief description of the locked breech pistol is in order.

The bullet and slidestart to move at the same time.

The slide pulls the barrel backward with it.

At 1/10th inch...nominally...the barrel reaches the very beginning of the linkdown point. At or just before this point, the bullet exits.

The barrel links down. At .250 inch of slide movement, the barrel is completely disengaged, and the slide continues to move rearward on conserved momentum.

Go to Page 1 and watch the video that I linked to on post #21. Pay special attention to the very last 1911 in the sequence...and at the x-ray picture of the pistol in operation in post #40, and note the position of the link.

PS

Kuhnhausen's Balanced Thrust Vector description is dead wrong. Can't happen.

so you're saying that the force of the pressure pushing back on the breech face is what pushes back the slide on a 1911, while the slide is locked to the breech? That's just not possible, any more than a piston, locked to a cylinder so that it doesn't move relative to the cylinder, will push the whole piston-cylinder assemble backwards.

p.s. I have no idea what Kuhnhausen's Balanced Thrust Vector is, but I do have a decent understanding of physics, and it seems pretty clear that a locked beech weapon can't be operated by the gas pressure in the barrel acting on the breech face.

so you're saying that the force of the pressure pushing back on the breech face is what pushes back the slide on a 1911, while the slide is locked to the breech?

That's exactly what I'm saying...and that's the reality. It's the only compelling force that's available.
There is nothing else that can do it.

And...The slide isn't locked to the breech. The slide is locked to the barrel. The junction of slide and barrel is the breech.

The slide is driven rearward, and the barrel is pulled rearward with it. Hand-cycle the slide on your pistol, and watch the barrel move backward a short distance and start to drop. That's exactly how it works when it's fired, except the force comes from within...between the bullet and the breechblock.

Go push on an object. The instant that you start to push, you get pushed. The force is supplied by your arm. Your body is one side of the action/reaction force pair.

Go pull on an object. You get pulled.


Better yet...Go watch the video.

I know that the barrel and slide move backwards together, that is why it's not possible for the gas pressure pushing on the breech face to be the force pushing the slide and barrel backwards.

think of it this way

the barrel is like a cylinder, that's open at both ends, with a piston in each end. One has low mass (the bullet) and the other piston has a large mass (the bolt/slide). In a straight blowback, the gas pressure inside the cylinder will accelerate both pistons. the low mass one will accelerate much faster, and the high mass one will accelerate more slowly. when the time the low mass piston leaves the cylinder, the gas pressure is vented, and the heavy piston continues moving back against the recoil spring because of it's momentum.

In a locked breech pistol, the heavy piston is locked into place, so it cannot move relative to the cylinder. What force is pushing the cylinder and piston that is locked to it backwards? The recoil force is.

it cannot move relative to the cylinder. What force is pushing the cylinder and piston that is locked to it backwards?

The slide is driven backward, and pulls the barrel backward with it.

What force is pushing the cylinder and piston that is locked to it backwards? The recoil force is.


We understand that. The question is...Do you understand what generates recoil?
Recoil is not a force. Recoil is the result of a force applied...just like bullet acceleration through the barrel is the result of force applied.

Force forward equals force backward. The only force that's available is the force that comes from the burning, expanding gasses.

. In a straight blowback, the gas pressure inside the cylinder will accelerate both pistons. the low mass one will accelerate much faster, and the high mass one will accelerate more slowly.

And what is it exactly that makes the locked breech pistol any different...aside from the barrel mass being added to the slide's for a short time? Exactly?

Go watch the video.

Ok, I guess you could consider it to be kind of like a piston inside of a piston.

yes, I understand what causes recoil. conservation of momentum is responsible for recoil, and you could also explain the rearward motion of the locked piston-cylinder system in terms of conservation of momentum, which would make the gun recoil operated.

I think this is a situation where you have to different models that both explain the same physical phenomena.

conservation of momentum is responsible for recoil, and

Nope. Conservation of momentum isn't responsible for recoil. Acceleration is responsible for recoil. Momentum isn't a force. Momentum is the result of mass times velocity.

Momentum doesn't make things move. Conservation of Momentum is what keeps them moving after they get moving. Objects don't move unless a force is applied. See Newton 1A.
"An object at rest tend to remain at rest unless a force compels it to move.

Again...There's only one compelling force available to set everything into motion. That would be the force that results from the pressure that is generated by the expanding gasses.

Ok, I guess you could consider it to be kind of like a piston inside of a piston.


How is the barrel a piston? I'm literally sittin' here shakin' my head in disbelief.

The barrel doesn't drive the slide backward. The slide pulls the barrel backward while the bullet is moving through it. The bullet's frictionally-induced forward drag on the barrel, and the slide moving in opposition is what locks the breech via the lugs. It's like locking your fingers in front of you and pulling in opposite directions.

It's been fun, but I gotta go to bed. 0400 comes early in North Cackalackey.

Ah! You watched the video. Interesting, what?

Read the next few paragraphs carefully.

Going by the response that you deleted...and I'm not tryin' to bust your chops here...just tryin' to educate you a little.

I know that the barrel and slide move backwards together, that is why it's not possible for the gas pressure pushing on the breech face to be the force pushing the slide and barrel backwards.

Why do you feel like the gas pressure/force can't push the slide backward? Again...It's the only force in the system. There is no other force in the system. While the slide and barrel are connected, they're essentially one mass. Think of it as a variable mass breechblock that "loses weight" when the barrel is disconnected. Here, it operates no differently than a straight blowback...except while the bullet is present...it's frictional resistance in the barrel is acting as a delaying mechanism...resisting the barrel's rearward move, and thus the slide's.

The bullet is moving forward...which means that the barrel can move backward. Because the slide is being driven backward by the force created by gas pressure...and because the lugs mechanically connect it to the barrel...the barrel moves along with the slide.

Grasp a broomhandle in front of you in both hands. Pull hard in opposite directions. Just when you're exerting a good amount of force...loosen the grip on the handle with one hand just enough to let it slip. When the handle starts to slip through your hand...your hand starts to slip on the handle. Now you have an action and a reaction. Before the slip....you had equilibrium from the balanced forces.

The broomhandle is the bullet. The slipping hand is the barrel. The wrist on the slipping hand is the locking mechanism. The forearm is the slide.

No, it doesn't matter that the compelling force comes from the outside...pulling both objects instead of from the inside pushing them. The "bullet" and the "slide/barrel assembly" don't know where the force is coming from. They only know that a force is compelling them to move in their respective directions.

To recap:

Momentum isn't a force. Momentum doesn't cause things to move. Force causes things to move. Momentum keeps them moving. Refer to Newton 1B...to wit:

"An object in motion tends to remain in motion unless an outside force is imposed on that object."

Here, Newton was describing conservation of momentum.

Recoil isn't a force. Recoil is the result of a force applied, and the acceleration that it suffered because of that force. Recoil is acceleration. Recoil only occurs during acceleration. Once the accelerative force is removed, and further movement is accomplished via momentum.

Once the bullet exits the barrel, the force goes with it. Neither bullet nor slide is being compelled to accelerate. They continue to move because of the momentum that they conserved during their acceleration...while the system was active...and they are now compelled by outside forces that are trying to bring them to a stop.

Finally:

In a locked breech pistol, the heavy piston is locked into place, so it cannot move relative to the cylinder

How can the piston be locked to the cylinder? If that was the case...bullet locked to the barrel...neither bullet nor barrel could move. If the barrel can't move, the slide can't move.

A savvy old pistolsmith up in Maryland conducted an experiment years ago in which he used a steel rod and a set screw threaded into the muzzle of a 1911 barrel. He designed the end of the rod to prevent bullet deformation...to insure that the bullet couldn't budge a fraction of an inch.

He fired the pistol...and nothing happened. The slide didn't move and the gun didn't burst. The pressure escaped around the breech with a slow hiss...but nothing moved. Here, the piston was locked to the cylinder. The cylinder couldn't move backward...and neither could the slide.

It was an attempt to disprove Kuhnhausen's balanced thrust/force vector theory...but in doing it the way he did...he actually created balanced forces. A system in which the compelling and resisting forces were equal.

This would all be really easy to explain with a clear plastic mockup of a 1911.. :D

I would like to know where you found that radiograph of the 1911 in recoil. That's interesting on multiple levels and worth using as a teaching point, both for 1911's and radiography.

I think that you couldn't take a picture like that today. The X-ray dose must be very high to go through the pistol.

My experiments (albeit with a weighted slide, not a fixed slide) show there is no difference. I explain it like this: There are four variables:

V1 = muzzle velocity (including gas velocity)
M1 = mass of the ejecta (projectile and gas.)

V2 = velocity of the moving parts (and ultimately of the gun)
M2 = mass of the gun.

The independent variable in the equation is V1 and the dependent variable is V2. By changing V1, you can change V2. But it doesn't work the other way. You can't change V1 by changing M2 or V2. At least not within the margin of error of the Shooting Crony I used.

He fired the pistol...and nothing happened. The slide didn't move and the gun didn't burst. The pressure escaped around the breech with a slow hiss...but nothing moved. Here, the piston was locked to the cylinder. The cylinder couldn't move backward...and neither could the slide.

I'm glad to hear this. Now I don't have to worry about my gun blowing up due to a blocked barrel. :D:D;)

Actually there's a much simpler, but less dramatic, way to demonstrate this.
You need a locked breech pistol that has an exposed barrel. (P08, P-38, Broomhandle, etc. A M1911 won't do because the barrel is enclosed by the shroud). Clamp the barrel in a vise, run a rod down the barrel until it contacts the breechface and push, nothing will come unlocked. In fact, you can beat on the rod with a mallet and the result will be the same.

I think that what is confusing some is saying that it is the "gas" pushing against the breech that makes everything operate. Think of the gas as merely providing the force. (Gas is ambivalent and will take the path of least resistance.) However the force created by the gas expansion follows Newtons 3rd Law and sends the bullet one way and the locked together slide/barrel the other. They will continue to be locked together until some mechanical linkage causes them to unlock. Then the residual momentum (Newtons 1st Law) takes over and the slide continues until stopped by the frame abutment/spring/buffer.

Think of the gas as merely providing the force.

That's the point I've been tryin' to make...but I ain't gettin' through for somed reason.

It's really no more than pneumatics and heat. As more air is pumped into the cylinder...pressure goes up...and at some point, somethin's gotta give. Either it will set the system in motion or blow it up.

This thread makes me appreciate the finer details that had to be understood and accounted for by J.M.Browning when he designed the thing.

Making a complex system managing the forces and timing in such a simple manner is genius.

(Of course that is kinda overstating the obvious.)

Making a complex system managing the forces and timing in such a simple manner is genius.

And the fact that Browning was never formally trained in engineering makes it almost mystical.

Well...Dang. That ended abruptly. And just when I was cocked and locked and ready to rock. :D

Since it took a sidestep for a couple pages...Let's review.

Kuhnhausen was wrong. The slide moves while the bullet is in the barrel.

Blowback and recoil operated pistols are both recoil operated. Force forward equals force backward.
The same force that dirves the bullet away from the breechblock also drives the breechblock away from the bullet.

No rocket science necessary. It's no more complicated than Newton's 3rd Law of action and reaction.

Recoil isn't a force. Recoil is the result of acceleration due to force applied, and once that force is removed...all further movement is on momentum. Newton 1B. "Objects in motion tend to remain in motion."

Momentum isn't a force. Momentum is a function of mass times velocity. An object doesn't have momentum until it's moving...and force is what moves things...not momentum. Momentum keeps things moving after they get started.

The only force available in an internal ballistic event comes from pressure that comes from expanding gasses contained within the cylinder...the barrel...that drives the bullet forward and the breechblock backward at the same time. (You can't push on an object without immediately being pushed, and the size of the force when pushing is returned to you in equal measure.)

In a locked-breech pistol...The slide pulls the barrel backward instead of the barrel pushing the slide. The barrel doesn't recoil. It's just along for the ride.

The bullet is the main delaying factor in a locked-breech pistol due to frictionally-induced forward drag on the barrel. This is the one that so many overlook. Whatever frictional resistance is offered to the bullet by the barrel...is offered in equal measure to the barrel by the bullet. Because the barrel is resisted by the bullet's influence...and because the slide pulls the barrel backward...the bullet is likewise resisting the slide. Newton 3 works in both directions...whether pushing or pulling. (You can't pull on an object without being pulled by that object.)

John Browning was a slam-dunk genius.

Cheers!

Pretty good synopsis, but I'm not sure if I totally agree with your statement
The bullet is the main delaying factor in a locked-breech pistol due to frictionally-induced forward drag on the barrel.
There are several factors that delay the unlocking, with the forward drag being just one of them. Others are time in barrel, weight of moving parts that have to react to force applied, strength of recoil spring, weight of the bullet. Even the weight of the gasses produced by the burning propellant charge and their expansion rate will have an effect.
I'm not convinced that bullet friction is the main delay factor.

Pretty good synopsis, but I'm not sure if I totally agree with your statement


I understand what is involved in the delay, dead...but the bullet outweighs all others combined.

Wanna prove it to yourself? Eliminate the bullet.

Load a blank with 10 grains of Bullseye, and put a tuft of cotton over the charge to hold the powder in the case. Work the blank into the gun and fire it. You'll be surprised at how far the slide will move with so little pressure and low mass on the other end.

Be sure and report back. ;)

Bullet weight, yes, I agree that it is the main factor affecting lock time.
I was disagreeing with your statement of bullet friction pulling the barrel forward was the main factor.
The bullet is the main delaying factor in a locked-breech pistol due to frictionally-induced forward drag on the barrel.
Maybe your wording of the sentence wasn't what you intended to say.

I was disagreeing with your statement of bullet friction pulling the barrel forward was the main factor. Maybe your wording of the sentence wasn't what you intended to say


My wording conveyed exactly what I meant to say.

Go push a bullet through a barrel...chamber to muzzle...by hand. The coefficient of friction doesn't lessen because the bullet is moving fast. Neither does it lessen because the bullet's momentum helps it along the way. It is what it is.

Whatever frictional resistance that the barrel offers to the bullet...the bullet offers to the barrel. The bullet moves through the barrel in one direction, and the barrel is pulled over the bullet by the slide in the opposite direction.

Think on it. Go load up the blank to see how little force is needed to move the slide without the bullet. Then, think on it a little more.

Then why won't my M1911 cycle with snake shot, leave alone blanks?

Dunno. Maybe the shot cup to barrel friction is delaying it enough to offset the force/mass/momentum thing.

Try the blank. 10 grains. I've only been as far as 7 grains...and the slide moved far enough to put the hammer on half-cock. Standard half cock and not a Series 80 quarter cock shelf. 10 grains may get it all the way.

Try this..or at least visualize it:

Grasp a broomhandle in both hands at shoulder height in front of your chest. Pull in opposite directions. Loosen the grip of one hand juuuust enough to let the handle slip.

When the handle starts to slip through your hand, your hand starts to slip off the handle. As long as you maintain a grip, there is friction between the two. i.e. Whatever friction that your hand imposes on the handle, the handle imposes on your hand.

Keep pulling and keep the system moving. As your hands move father apart, you'll notice that the hand's movement is resisted by the handle...and the handle's movement is resisted by the hand.

The broomhandle represents the bullet. The slipping hand represents the barrel. The forearm attached to the slipping hand represents the slide. See it yet?

I fully understand your analogy with the broomhandle and I agree that a blank will provide enough force to unlock the slide and barrel, but there is not enough force to cycle the action. To obtain enough force there has to be enough mass to provide something for the expanding gasses to build up force. A blank, and in my case shot just doesn't have enough to do this. Especially with a blank where there is negligible barrel friction, if any.
Your example is to take away mass but keep the friction to provide something for the pressure to work against. This will work only if there is enough friction. I contend that if you take away friction and leave mass, the action will continue to cycle, albeit probably too violently for the design of the gun. As to which is the primary factor in operation, I will go with mass over friction. What the balancing point between more friction, less mass vs. more mass, less friction, I don't know. It would be interesting to do some empirical testing.
In both examples, if you take them to the extreme, i.e. sufficient friction or mass to allow the pressures to build beyond the strength of the gun, you will end up with a burst chamber. If the chamber and lock are strong enough to contain the generated pressure, nothing will happen. Presuming a perfect seal, how long the pressure would remain would be an interesting experiment.
I have to assume that it would remain until someone opened the chamber.;)

Dead...Yer still missin' the point. Without the bullet, the slide and barrel don't lock.
The barrel lugs engage vertically, but they lock horizontally...under pressure and friction.
Lock your hands in front of you and pull. Like that.

About 2 years ago, I was watching a lady shoot the falling plate machine while I talked to her husband. I was looking straight at the gun when I heard a muffled pop. I saw the slide cycle...saw the empty case eject...watched the slide go back to battery.

Before I could stop her, she fired another round...and the gun locked up solid. It barely made a sound.

Two bullets nost to butt an inch from the muzzle with a big dog knot jammed into the bushing. Barrel split from third lug to muzzle at 9 and 3.

A squib cycled the slide far enough to chamber another round.


You can move it by hand with relatively little effort. Right?

Even as fast as you can rack it, it doesn't take garguantuan strength. Why? No bullet.

Try the 10-grain Bullseye/cotton blank. You might be shocked at how little force it takes to move the slide without the bullet's presence.

if you take them to the extreme, i.e. sufficient friction or mass to allow the pressures to build beyond the strength of the gun, you will end up with a burst chamber.

The demonstration that I described with the steel rod blocking any bullet movement in the 1911 was performed by our own Jim Keenan...but it wasn't entirely his idea. Several years before, it was done by...if memory serves me...Charles Askins. The difference being that he did it with a 1903 Springfield rifle...and nothing happened.

Awwww! C'mon dead. It'll take all of 5 minutes and a nickel's worth of components.

OK, I did it. It pushed the slide back far enough to partially extract but not eject the case. All it shows me is there was enough mass in the cotton and expanding gas to create enough force to partially operate the gun.
I would imagine that you could get a better result using an oversized wooden bullet. (More friction while minimizing the mass.) Of course I can maximize mass and minimize friction by using a smoothbore with a slightly undersized bullet.

Both ways will work, but what does it prove? You can no more eliminate mass than I can eliminate friction.
Sounds like we are arguing about how many angels can dance on the head of a pin.

Both ways will work, but what does it prove?

Well...it provces a couple things. One is that the locked breech/recoil operated pistol works just like a straight blowback when the bullet doesn't influence the slide delay, and it proves that the slide doesn't require a helluva lotta force to cycle it without the bullet's influence.

Now, go load up a live round using a 185-grain bullet and about 3 grains of Unique. The pressure is much higher than with the blank...and the mass is much greater...but you may find that the slide moves about the same distance.

I'll say it again. The bullet is the greatest delaying factor in the locked breech pistol...and if you can't see it...it's because you refuse to see it.

But, I'll try again...just for the sake of greater understanding.

Hypothetically, of course.

Loaded cartridge...Drill a hole in the bullet and thread in a cable that won't pull through the bullet core. (This is unobtanium alloy that makes up the core.)

Load the cartridge in the gun and put it into battery.

Attach the cable to a steel block that weighs about a ton. Lock the frame of the gun in a vise that's bolted to a table that weighs about a ton. (We don't want any slippage that would give a false result.)

Pull on the slide until it moves backward. Yes. It can be done if you can exert enough force to move it.

You can even remove the recoil system and cock the hammer to eliminate any other delaying factor if you'd like.

You'll have to pull harder'n a billy goat can butt a stump to move that slide...against the resistance that the bullet offers to the barrel. I guar-on-tee.

One last experiment, Dead...then I'll leave ya to your thoughts.

If you've got a .44 die set...size the case first in a .45 die. Then run it into the .44 die about a quarter-inch. Then...if you've got a .41 die set...neck it down to that size.
Now, try the 10 grain load and the cotton tuft. It'll probably lock the slide on an empty magazine. It may do it without necking down to .41 caliber.

What you do here is create a venturi effect. While it does raise the pressure a bit...pressure isn't the driving force. Mass times velocity is. Raise either one, and there is more force. More force forward equals more force backward. More force backward equals more slide travel.

Straight blowback...Recoil operated...All same-same. Both are recoil operated. The only difference is the mechanism used to delay the breech opening.

Well maybe if I go stand in the corner on one foot, hold my tongue just right and squint my eyes, I'll see it your way.:D

BTW It wasn't a Springfield that Askins experimented with. It was a Japanese Arisaka. He ended up running a 30/06 chambering ream into a 6.5 Jap loaded it with a case full of Bullseye and a .308 bullet. The barrel was set forward two threads, the case flowed back around the bolthead to the point that he broke the bolt handle off trying to open it, the stock shattered. but the receiver held. No blowup.
Supposedly he later rebarreld the action and continued to use it.

Ahhh! You just don't wanna accept what your eyes are tellin' ya. :neener:

First, there was no way that 10 grains and a cotton plug could possibly move the slide...but it did. You still don't believe that the bullet is the major player in the delay...but it is. I got faith in ya, though. the light will come on if ya think about it long enough.

Okay. It was an Arisaka. Been a while since I read it. The point was that the rifle didn't move. No recoil. The effect of bullet delay was taken to a level that completely blocked all barrel movement rearward...and if the barrel can't move rearward...the gun can't kick.

On the other hand...if he'd blocked the bullet by a method that was divorced from the gun, it would have recoiled...because the force would have pushed the rifle backward and the barrel would have been pulled off the bullet. At least, for a short distance. It's also likely that the barrel would have been ringed or bulged behind the bullet...but that's a matter of conjecture. I ain't gonna run the test to find out.

I am having trouble with the bullet drag explanation and the effect upon the function of the 1911. If the barrel/breach, and cartridge are isolated as a system, it seems to me, that when all the forces are resolved, the following occurs. There is the pressure or force pushing on the base of the projectile mass and the barrel/breach. This results in the acceleration of the the projectile mass and c/g of the expanding gas in one direction and the barrel/breach in the other. The friction between the projectile mass and barrel/breach results in the acceleration of the projectile mass and barrel/breach in their respective directions, to something which is less than the theoretical acceleration for each. To the observer outside of the system, the net effect is that respective velocities of the projectile and barrel/breach are less than theoretical. Is this difference between the theoretical and actual acceleration, the projectile/barrel drag that is being referenced? Is the drag more important than the mass of the barrel/breach in delaying the unlocking? Sorry, if I am missing something that has been explained before. Thanks

RBANNON...Wow. I don't know if I can follow all that...but I'll try to resolve your confusion with another analogy/hypothetical thing.

Let's morph you down to a tiny size...small enough to sit between a projectile and a breechblock. Forget the case for a minute.

Let's also give you superhuman strength. You're so strong that you can accelerate the
bullet and breechblock at normal velocities. Let's also give you arms that elongate, so that you can push the bullet completely out of the barrel.

If you stand between the two interacting objects and push...you feel a resistance on both arms. One from the drag between bullet and barrel...the other from the slide pulling the barrel backward on the bullet.

Now...go back to the normal operation of the ballstic event and consider what we know:


1. We know that the bullet and the barrel are moving in opposite directions at the same time. That's a given.

2. We know that the slide ain't gonna stand still...wait for the bullet to leave...and then move. That's another given.

3. We know that the bullet ain't gonna stand still until the barrel and slide finish their thing...and then take off.

4. We especially know that the bullet ain't gonna start...stop...wait for the slide and barrel...and then take off again.

We know that it takes a lot of force to push the bullet through the barrel. Therefore, it only stands to reason that it requires the same level of force to pull the barrel backward over the bullet...which brings us back to square one.

Whatever frictional resistance the barrel offers to the bullet, the bullet offers to the barrel...and...whatever resists the barrel's rearward movement also resists the slide.

Do the broomhandle trick that I outlined earlier. It'll start to make sense after a few times.

I know that it's hard to visualize because things are moving fast and the bullet's drag and delay only lasts for 1/10th inch of slide travel...or less. But if the bullet and barrel are moving in opposite directions at the same time...it has to work that way.

Wow Tuner, still on the bullet friction locking kick, huh? The simple fact of the matter is this:

1) round is fired
2) ignited round exerts pressure on breech face, pushing slide and barrel
in opposite directions under pressure, "locking" slide lugs and barrel lugs.
3) slide begins to move a slight amount as bullet is still in barrel
4) pressure drops as bullet exits muzzle
5) slide and barrel(locked as one unit) continues to the rear due to recoil
forces (it is "recoil operated")
6) barrel links down from slide, allowing slide to continue

I have been reading some old posts on this "friction locking" and I thought
a poster by the name of "SDC" had proven that this friction locking was false.
The barrel and slide lugs stay locked together because of pressure on the breech face forces the slide and barrel together as in the xray of the firing 1911. The slide is "pulling" the barrel back and the only thing that delays it
is the fact that the slide moves many times slower than the bullet that's speeding out of the barrel.

I saw a question poised to you as to why a
bored out barrel with minimal friction still functions 100% but you never answered it. I also saw a post where you stated it was in Mr. Brownings
patent, but you could never post anything from the patent that
showed that "friction" was a major factor in locking the breech. In fact you
say; "The bullet is the main delaying factor in a locked-breech pistol due to frictionally-induced forward drag on the barrel. This is the one that so many overlook." The "main" factor? Where does it say this in Brownings patent? And why does a smooth bore 1911 function normally? Why isn't the 1911
called a "friction lock".

Also, didn't some guys here take some readings as to how much force it took to ram a fmj down
a 1911 barrel and it came out to be about 5% of the total psi involved in cartrdge firing? How
is that a "main factor" in locking

Sure am, guru...because it's a fact.

The slide doesn't require a lot of force to drive it without the bullet's influence. Load a blank with 7-8 grains of Bullseye and a tuft of cotton and see for yourself. You can hand-cycle the slide faster than it moves when the gun is fired.

In case you didn't get it the first 15 times, I'll try again.

The barrel offers frictional resistance to the passing of the bullet. Whatever frictional resiistance the barrel offers to the bullet, the bullet offers to the barrel. The barrel has to move backward WHILE THE BULLET IS MOVING FORWARD...each one resisting the other's movement. Regardless of how short that distance is...while they're moving in opposite directions...both motions are being resisted by the other.

The barrel engages vertically...but it locks horizontally when the gun fires....

AND...

It does say so in Browning's patent. If you'd taken the time to actually read it, you'd have seen it.

Cheers

You still haven't answered my questions. This is what you did in other threads also. Where is the SPECIFIC wording about friction locking
that Browning includes in his description? Also why does the smooth bore
1911 function with minimal friction of the bore?

This is the thread I was talking about:

http://www.thehighroad.org/showthread.php?t=290427&page=13&highlight=1911+vector

Do you have any numbers to back up your statement that the friction
in the barrel is "the main factor" in locking? If that's the case then
a smooth bore 1911 would basically be a blowback, correct?

Guru...I never said that it "friction locks." That's your interpretation...your words.

It pressure locks. Barrel under forward drag by bullet friction. Slide driven backward due to force applied. Lugs are engaged in opposing directions. Barrel is pulled backward by the slide due to lug engagement...or pushed, depending on your perspective. Barrel is resisted by bullet drag. Whatever resists the barrel's movement resists the slide's movement...because the slide is taking the barrel backward with it...at the same time that the bullet is moving forward through the barrel.

Again...The locking description is in the original patents. Go and find it. It's there.

Imagine this:

If you had a bullet lodged in a barrel...and the bullet had a cable through the center of it...and the cable was attached to a wall...how much force would you have to use in order to pull the barrel off the bullet?

Now go find it in the patents.

1911tuner is right, pressure in the barrel would push the breechface, and thus the slide back, but not the barrel. The only force acting on the barrel is the friction, which acts in the opposite direction.
I don't know if the friction is the main factor, but it definitely plays a part.

You said the barrel is pulled into lock("main factor") with the slide by friction of the bullet to the bore. That's not correct. It's locked into the slide through pressure from the firing cartridge. You still haven't answered my questions, by the way. Why does a smoothbore 1911 function normally when friction
is the "main factor" in locking?

I will search the patent also.

SaMx, that's exactly what I said, but he said friction in the bore is the "main"
factor in locking. It is definitely not.

Shoot a string semi-auto and another string holding the action closed with your thumb on the operating handle or slide.


Can you actually do that--hold the bolt closed with your hand and not get hurt? Is this possible for the low energy .22lr only or can it be done with centerfire pistols as well?

but he said friction in the bore is the "main"
factor in locking.

No, I didn't. I said that friction in the barrel is the main SLIDE DELAYING factor. It's more signifigant than all the others combined. More than the recoil spring. More than the mainspring. More than slide to frame friction. More than wind resistance...combined.

The lock comes from pressure trying to drive barrel and slide apart...prevented by the locking lugs under a shearing force.

Lock your hands in front of your chest and pull in opposite directions. Clue: Your hands represent the lugs in opposition....and each hand is resisting the other. That's how it locks. The gun isn't locked when it's static, in battery. It locks when it fires.

I'd suggest that you go find it in the patents again...but at this point, I don't think you'd believe Browning either.

Ok, this is for 1911...

I have always felt that every semi-auto handgun I have ever fired has a 'preferred' grain weight projectile for a given powder load. This discussion on a friction force vs. time delay seems to firm up what I have always thought 'because dammit, it seems right'. I always assumed that the deciding factor would be something like the twist rate on the rifling, but I guess that goes into the friction.

And reading this is just pushing me more in the direction of reloading so I can load up some for proving that theory.

And no, I would not want my hand in an x-ray that could go through even thin steel. Then think of how many shots it took to get that 'one'...

If the friction is the main DELAYING factor as you say, then the aforementioned smoothbore 1911(that you conveniently failed to answer my question about again) would be a blowback correct?

The SLIDE mass(AND PRESSURE) is the main delaying force. It moves much slower than
the bullet. Get it? The smoothbore 1911 would not blow brass or show
any signs of premature unlock BECAUSE FRICTION HAS NOTHING TO DO WITH IT. :mad:

guru...Any friction imposed on the barrel by the bullet would work to delay the backward acceleration of the breechbolt. Low friction...high friction...medium friction. The only difference would be in how much resistance and delay is imposed by the passage of the bullet. Even air offers friction. That's why meteors burn when they hit the atmosphere...and that's why bullets in flight slow down.

I'm gonna try this one more time, and then I'm movin' on to other comments and questions.

Imagine a cork in a pipe with a rope attached to the cork. Tight fit, but moveable through arm strength. One hand on the pipe and the other on the rope. Pull them apart. As the cork starts to move, so does the pipe. Keep pulling and keep them moving. The cork is being resisted by the pipe and the pipe is being resisted by the cork...because they're in contact and moving in opposite directions. Simple.

The cork is the bullet. The pipe is the barrel. Your arm...locked to the barrel by your grip...is the slide. The slide arm) is being resisted in its travel...by the bullet(cork) and friction provides the resistive force. Because your arm(slide) is resisted in its rearward acceleration...it's being delayed. (slowed)


Newton 3 works in both directions...whether pushing or pulling. Friction works in both directions, too. Whatever friction is imposed on one is imposed on the other. When you slide a steel block across atable, both table and block "feel" friction. Friction is a resistive force

And, just to wring your head up a little tighter...A straight blowback pistol is also recoil operated. The only difference between the blowback and the recoil operated pistol is the method used indelaying the opening of the breech. Aside from that, they both function as a result of force forward and force backward.

Be well.

Duvlarian...The short recoil operated pistol only provides acceleration on the system for a brief instant. The slide moves nominally about a 10th inch when the bullet exits. When the bullet exits, all force is removed from the system, and neither bullet nor breechbolt...the slide...are feeling acceleration. All further movement is due to momentum. The slide gains speed...and momentum...during the time that the accelerating force is on the system. Recoil is nothing more than backward acceleration.

Most of what we perceive as recoil is actually momentum that results from the recoil impulse and acceleration of the gun. The true recoil is over so quickly, that our brains don't have time to realize that it happened before we detect momentum. Remember...Once the force is removed, there is no more acceleration.

If a bullet of a given weight is driven to a given velocity, that means that it had to be accelerated to that velocity, and it's entirely possible that a bullet is actually moving faster before it exits the muzzle than at the muzzle...depending on several factors.

In order to drive it to a higher velocity in the same barrel length...more force is required to accelerate it to that speed. If a lighter bullet is substituted...the force requirement drops...and because force forward equals force backward...the lighter the bullet for a given velocity the lighter the recoil impulse. In order to obtain the same recoil impulse, the bullet must be driven harder...accelerated more quickly...with the resulting higher escape velocity.

Anything that resists the bullet drives up the force requirement...including a faster twist rate. Bullet X in a cartridge that is loaded to a maximum pressure in barrel Y with a 1:12 twist rate is safe. The same cartridge in Barrel Z with a 1:6 twist rate may not be safe. As resistance goes up, pressure spikes more rapidly. Think of it as a sudden bore constriction, and it'll make sense. That's why it's imperative to develop maximum loads in the gun that they're intended for. One little change...a .0005 inch tighter bore...and pressures could go into the red zone.

I'm not looking for maximum loads. More precisely, I feel that each gun handles fractionally better with particular weight and powder charges. I am more looking at accuracy.

Not a pure guess, an observation of several thousand rounds of factory ammo. I would not say that I am an expert by any means, but I am rather consistent.

If you are saying that the frictional constants combine together to give a fixed delay when combined with the inertia of the slide and the strength of the recoil spring ... it would stand to reason that a particular grain weight of projectile and powder charge would give an optimal performance. Not just a single combination, but a separate combination for each make and caliber. It would also vary slightly based on individual wear, but it should work out to be fairly constant for each different make and caliber (not accounting for individualized modifications).

From the video you posted, shooting from a rest at about the 2:30 mark, there is the smallest of upward motion in the barrel before the bullet exits. That's pretty much what I am looking at. Basically, if you can have the bullet exit the barrel before slide starts to rise from the rearward motion from the recoil you should have an improved accuracy. Lol, well, that's the thought anyway.

Ah! Okay. If we're on accuracy, then, yes. Most guns have a preferred load as to bullet weight, shape, powder charge...and even cases and primers.

The "recoil" spring doesn't really have that much effect on slide/breech opening delay. The mainspring actually has more effect.
Its static resistance...preload...is only about 8 pounds with a 16-pound spring. Compressing it an additional 1/10th inch isn't going to add a lot to that. Of course, any opposing outside force means something...but the spring doesn't figure that much.

Ned Christiansen once fired a Delta Elite repeatedly without a recoil spring without adverse effect on the gun.

The primary function of the recoil spring is stripping, feeding, and returning the gun to battery...not delaying or decelerating/buffering the slide. It does do that as a function of compressing...but that's incidental. It has to be compressed in order to perform its main function. I much prefer "Action Spring" to recoil spring...but it's been called that for so long that I just go with it.

On the video...Notice that the bulk of muzzle flip...which accounts for the felt recoil...occurs when the slide hits the frame? Before that, the gun moves very little.

Even firing all guns at once, a WWII era battleship suffers no displacement laterally from it. Does that mean no work was done on the ship by the massive energy absorbed by it in firing 20,000 lbs of projectiles at basically high-powered rifle velocities (I believe around 3000fps)?

Perhaps not a good example, as seen in the picture linked below. A full broadside is a LOT of kinetic energy and overcomes the inertia of the ship enough to kick up a bit of sideways wake.

http://en.wikipedia.org/wiki/File:BB61_USS_Iowa_BB61_broadside_USN.jpg

Mark...Exactly. It would serve also to bear in mind that the recoil of the guns not only has the mass of the ship opposing it, but the water that the ship is floating in as well...and after adding the surface area of the keel...that resistance is considerable.

Like pushing on an oak. You can't move it because you couldn't exert enough force...but that doesn't mean that the tree didn't have a force imposed on it.

Thanks for the education. I'm seriously impressed.:cool:

Didn't mean to come off so hard but and I appreciate the replies.
I just want to understand what you are saying. The friction of the slug
in the barrel is the single largest delaying factor for the slide/barrel,
correct? So, it would be safe to assume that the slide/barrel assembly
would move further back earlier in the bullets travel down the bore(maybe even far enough to unlock while the bullet is in the barrel) if the bore was smooth and friction minimized, correct? This would result in bulged and possibly blown brass since it is the single most important factor in slide delay(according to your theory).

I have not heard of this happening in the few instances I have read about here and on other boards. In fact, there have been reported nothing abnormal in the functioning of the 1911 with a smooth bore. This is because the momentum of the stationary slide(and hammer spring and barrel to a smaller extent) prevent the slide from moving except for a small amount while the bullet is in the bore. Keep in mind that the speed of the bullet is many times faster than the slide. The friction of the slug has a negligible effect.

As you have said, "believe the experiment, not the theory", or something to that effect.

The barrel can't unlock while the bullet is still there and under pressure. Pressure...Force forward and force backward...with the lugs engaged in opposition is what locks it. Delaying the slide gives the bullet time to exit so that the presure can drop, and the breech can open without blowing the case.

Once the pressure is off the system, the lugs are no longer being forced together in opposition, and they're effectively unlocked. At that point, the barrel can be linked down and the breech safely opened. The unlock occurs before the linkdown point...not at the linkdown point. Again...the barrel being vertically engaged in the slide and the slide in battery isn't locked. It engages vertically, but it locks horizontally when the gun fires.

There are several factors that are at work in delaying the slide. Since the instant an object is set into motion, outside forces immediately begin working to bring it to a stop, and anything that can bring that about will do that eventually.

I think that the cork in a pipe analogy has flipped on a light for you. It has to happen.
The bullet is a tight fit in the barrel. (Friction) The bullet is moving in one direction and the barrel is moving in the opposite direction...at the same time. Whatever resistance that is offered to the bullet BY the barrel is also offered to the barrel by the BULLET.
Whater resists the barrel's movement resists the slide's. The slide is delayed. Note that "delayed" doesn't equate to "Stopped."


The pressure lock description is in the patents. I suspect that you found it. FWIW, I understood the lock function years ago. Hard to believe, but I only got into the original patents sometime last year. I can't recall, but I think the bullet-induced delay is also described, but it's in lawyer-speak and requires a little careful thought before it's clear.

Actually, this "bullet induced" delay is not described anywhere in the
patents. I skimmed it carefully and did not notice this anywhere. Alot of what you are telling me I know already, for example:

"The barrel can't unlock while the bullet is still there and under pressure. Pressure...Force forward and force backward...with the lugs engaged in opposition is what locks it. Delaying the slide gives the bullet time to exit so that the presure can drop, and the breech can open without blowing the case."

I am fully aware of this basic operating principal. I never said I disagreed
with pressure locking. I just said I disagreed about the significance of bullet
friction on the operating; specifically, the delay of the slide/barrel assembly
after a round is fired.


The momentum of the stationary slide/barrel assembly is the main delaying factor in the slide's travel, along with resistance from the hammer and various frictional forces. The key to understanding this is the fact that the bullet
is traveling many times faster than the slide and is a fraction of the mass
of the reciprocating assembly.

I've asked maybe 4 or 5 times already; Why does a smooth bore 1911 show no pressure issues and functions normally if the friction of the slug in the bore
is the main factor in the delay of the rearward movement of the slide?

Why do you chose to ignore what is in my opinion the most important question?

Look at it this way...

The only alternatives are:

The bullet exits before the slide moves, ala Kunhausen's Balanced Thrust/Force Vector" description. Newton 3 says that can't happen, and the X-ray pretty much disproved that theory.

Or...

The bullet starts...stops and waits until the slide and barrel finish their cycle...and starts again. That can't happen either.

Or...

The bullet and barrel are moving apart at the same time, each one resisting the other's direction of travel because they're being forced apart against the frictional resistance that each offers to the other. Go back to the cork in a pipe analogy...or rig up an experiment and do it. When you're pulling them apart, you feel a resistance in both directions. The cork makes it hard to pull the pipe and the pipe makes it hard to pull the cork. What happens in the locked breech pistol works the same way.

Because...

Force on one side of the system equals force on the other side. That applies whether it's a compelling force or a resisting force...whether pushing or pulling.

It's all about delaying the slide until the bullet escapes. Delay...to slow or retard a function or action until a later time.

Just for what it's worth...The friction induced delay is the hardest part of the function to understand and make understood. Because it happens so fast, and only affects the slide for a very short part of its travel, it's hard to grasp. Just because it happens fast doesn't mean that the friction and the resistance disappears. It can't. The two parts are in contact. Friction is a force that can't be ignored. High friction. Try to push a bullet through a barrel. Which direction does the barrel want to go? Forward. Which direction does the slide pull the barrel? Backward. The bullet is doing its level best to hold the barrel forward while the slide is pulling it in the other direction.