A Physics Primer

[barrow]

Tark, theres no doubt that the slide and barrel have moved in that picture. look at the lower barrel lugs. Theyve backed a good ways off the slidestop pin.

 

[1911Tuner]

Why do you believe that a musket barrel recoils but a 1911 barrel with a welded breech (a muzzleloader by any other name) won't?

I never said that it wouldn't. That's what you seem to believe...that a welded plug in the breech of a locked breech pistol won't move the slide. I maintain that it will...just like the musket.

And be sure to use a bullet when you do this thing.

 

[Jlr2267]

{The term "recoil operated", in contrast, describe how firing energy is transformed from pneumatic to mechanical in a way to unlock the action and extract the case by secondary means. It is not able to "blowback" the casing by virtue of being locked at time of firing, so we do not call it blowback. That mechanical energy is from a recoiling mass, hence the term "recoil". That mass can be made to recoil from a variety of propellant means that don't have to be gas pressure, which illustrates the point further that the blowback derived energy part is unnecessary in the definition.}

I agree with this. However, "blowback" designs can be conceived which would function without expanding gas as well, so it is clear that this is an argument over semantics.

We all agree (I think) on how the actions operate, and the physical forces which control them...the rest is just arguments over traditional nomenclature.

 

[1911Tuner]

Both of these guns have locked breeches but blowback for extraction.

I take it you've never seen a 1911 or a Browning High Power function without an extractor.

Some of'em will. It's a matter of timing. If the barrel will drop with a little residual pressure remaining, the case will blow right out. Ejection is a little wild, but some of'em will do it.

Look...I'm not tryin' to say that there's zero difference. I'm sayin' that there isn't enough difference to argue over.

I'm sayin' that all three basic designs operate from force backward.

Recoil is no more than acceleration from force backward. Force drives the bullet forward and force drives the slide backward. In that respect, there's really no difference.

 

[RX-79G]

I don't think we all agree. I think you, me, Barrow and 45Auto agree on most points.

I think 1911Tuner accepted a bet that a muzzleloading 1911 wouldn't cycle. If he understood at the time what he may or may not accept now, he wouldn't have made that bet. But he did not agree when he made that bet.

I think 1911Tuner and a couple of others believe that barrel friction is somehow significant, and it is not. Relative to the other forces involved, barrel friction is a small player in traditional recoil operation.

It is a significant force in a FiveSeven, where the muzzle velocity is up above 2000fps on a bullet with a very high ratio of bearing surface to mass.

 

[JohnKSa]

I am STILL waiting for someone to show me 10,000 frames per second photography showing ANY movement of the slide on ANY automatic until AFTER the bullet has left the muzzle.

Here's one. The video in the link below is a compilation of several slow-motion videos of firearms being shot. One segment of the video (from 2:13 to 2:37) shows an extreme slow motion closeup shot of the muzzle of a 1911 pistol. The frame in this shot is held motionless and the dustcover is visible at the left of the shot.

It is plainly obvious that the slide/barrel have started to move long before the bullet exits the barrel. There is noticeable movement for 8 or 9 frames of the video before the bullet is visible at the muzzle.

http://www.youtube.com/watch?v=kq-xcqs5NIk

 

[RX-79G]

Thanks for the video, John. Unlike the fluroscope one, the gun is in a rest so the effect of the shooters hand recoiling and rebounding doesn't mask the slide motion.

 

[tark]

Barrow, you're RIGHT! It does look like it has moved! Oh, my god! did somebody on this thread just admit that maybe he does NOT know everything? (me) I may have to re-align my thinking. But I am mystified why all those high speed photos show no movement until the bullet is gone. In one I saw on the military channel, they showed a custom 1911 with front serrations on the slide(which made it very easy to index the slide to the frame) with the camera on the port side. The field of view was about three feet either side of the gun. You could clearly see the gas cloud emerging from the barrel and the bullet emerging out of, and exiting the field of view. And there was STILL a delay before the slide finally moves. I don't get it.
But I do know THIS If you plug the bore in Tuners experiment I think you will get a little more violence that just gas hissing around the breech as the pressure bleeds off.
Tuner if you're listening (I know you are) why do 1911s blow up when a squib load pushes a bullet just far enough up the bore to chamber another round behind it. Don't tell me it doesn't , I've seen too many of them come into our shop.

 

[tark]

johnKSa Thank you! Now I,ve seen one. I will now re-align my thinking.
Although i will point out that is a compensated gun with a ported barrel. Those things run on the ragged edge. The ports and compensater bleed off so much energy you have to put a ridiculously light spring in them to get the damn things to cycle. We've built thousands in our shop over the years and a .45 comp gun will go from a 16 lb spring all the way down to an 11. Then you have trouble having enough spring to chamber rounds reliably. My point being; If you took the comp and the ported barrel off and put a heaver spring in the gut that slide might not be moving quite so quickly.

BUT....I did say ANY PICTURES, didn't I? And you showed me one....
Had to edit again, the close up of the 1911 muzzle later in the video is really clear. Yep. I was wrong and at least i'll admit it.

 

[RX-79G]

Barrow, you're RIGHT! It does look like it has moved! Oh, my god! did somebody on this thread just admit that maybe he does NOT know everything? (me) I may have to re-align my thinking. But I am mystified why all those high speed photos show no movement until the bullet is gone. In one I saw on the military channel, they showed a custom 1911 with front serrations on the slide(which made it very easy to index the slide to the frame) with the camera on the port side. The field of view was about three feet either side of the gun. You could clearly see the gas cloud emerging from the barrel and the bullet emerging out of, and exiting the field of view. And there was STILL a delay before the slide finally moves. I don't get it.
But I do know THIS If you plug the bore in Tuners experiment I think you will get a little more violence that just gas hissing around the breech as the pressure bleeds off.
Tuner if you're listening (I know you are) why do 1911s blow up when a squib load pushes a bullet just far enough up the bore to chamber another round behind it. Don't tell me it doesn't , I've seen too many of them come into our shop.

Tark, the effect of a hand holding a pistol may actually make the slide recoil compared to the frame less, but the overall movement of the slide is the same. The shooter is going to take some of that recoil by letting the frame go back with the slide, then the frame comes to rest or is even driven forward by rebounding out of the hand. Either way, it doesn't change the central premise of recoil operation - the slide starts moving immediately, regardless of whether the frame follows for a bit or not.


As far as the chamber blow outs you're talking about, what was the chamber pressure? If the first squib caused setback of the next loaded round, then the chamber pressure went above specs. Otherwise, any locked breech gun should be able to contain the maximum chamber pressure, which shouldn't go much over maximum regardless of how much the bullet moves or doesn't.

Any locked breech gun that blows cases out just because it isn't allowed to cycle is improperly built.

 

[Jlr2267]

Any recoil-operated firearm design will work without expanding gas.

That is not true. A 1911 will not function without (a) an expanding gas propulsion system or (b) changing the gun design to a different propulsion system

A recoil-operated design can be applied to any propulsive system (gas, magnetic, spring-powered, electric, etc).

Yes, but changing the propulsive system is *changing the gun design*.

I think what you meant to say was that a recoil-type action can be designed around any type of propulsive system, which is certainly true....and in the same line of thinking, a blowback type action could be designed around any type as well (although it would be more challenging, in my opinion)

 

[RX-79G]

Yeah. Not real proud of that, but I wasn't a moderator then and I wasn't even into the gun boards all that much. I signed on here mainly out of boredom and made a few posts...and Handy jumped on me like a duck on a June Bug with a full measure of his typical snark. Don;t know why he singled me out, but there it was.

Missed this earlier. I imagine that Handy "singled you out" because you made an argument that the link on a 1911 is redundant and unnecessary. You made it on this board and you made it through an intermediary on 1911forum. Like you frequently do, you forcefully argue something false and went to some ends to discredit your opponent, in that case resorting to name calling, like "welp" or your more recent "dustup".

And, as we're already seeing on this topic, you will quietly change your tune and deny ever having insisted what you belittled others for not believing.


I've ended up reading a lot of old Handy posts on TFL and THR, as well as your body of work. It doesn't appear you knew anything about him when you decided to Troll him. Here's a thread that might tell you something:
http://thefiringline.com/forums/showthread.php?t=166600&highlight=poster

 

[tark]

RX79G , The guns we get in the shop blown up by squibb loads leaving a bullet in the bore (by squibb I mean primer with no powder)always have a ringed barrel, about an inch or so AHEAD if the chamber, where the second bullet hits the first. It seems to always blow out the bottom of the case in the throat area, along with the magazine, the grips and the shooters hand.
But my point is the primer almost always pushes the bullet an inch or two up the bore, so I think (I don't know for sure, I was wrong earlier on this thread) the increased pressures are due to a bore obstruction and not the bullet in the second round being pushed further into the case.
I DO know that tuners claim that he fired a 45 1911 with the bore obstructed so completely that the bullet could not move at all, resulted in no damage to the gun other that some hissing around the breech as the pressure slowly bled of; is most difficult to believe.

 

[Nom de Forum]

I didn't invent the term "locked" or "blowback". I'm merely explaining what they mean. And an unlocked, blowback action is defined by the fact that the action opens immediately upon application of chamber pressure, and that the speed the action opens is in direct proportion to the chamber pressure. More pressure, faster opening.


The blowback action does not immediately open upon application of chamber pressure. Not until pressure is sufficient to begin to overcome the inertia of the slide does the action “unlock”.

A locked breech system doesn't open due to chamber pressure. And the speed the action moves in a recoil system is also independent of chamber pressure. If you got 1000 fps out of detonation or a long, slow, low pressure burn, the slide and barrel will recoil at the same speeds.

Agreed. I do think that residual pressure aids slide movement after it unlocks.

This may be part of the problem.

In this case, you are misunderstanding what's happening. If the blowforward gun's frame was clamped to a vice and the barrel plugged, the gas pressure would still allow the casing and barrel to expand away from each other. Since the casing has nowhere to go, the gas pressure in the barrel pushes it forward. Friction certainly can assist with this, but it isn't necessary. Blowforward will work with a low friction sabot.

That is because your “plugged” barrel is mimicking essentially what a bullet in the barrel creates, a temporarily plugged barrel. Of course after the bullet exits the barrel the residual gas pressure will act upon the portions of the barrel perpendicular to the direction of the gas flow. I think Kumaso Hino and Tomisiro Komuro would agree with me.

The barrel friction thing is just part of the 1911tuner's confusion. You can create high friction, low mass projectiles that won't cycle a recoil gun because they have all the gas pressure but none of the momentum. And you can create low friction, high mass loads that will cycle everything.

That's the problem with belief. You believe that whomever named "recoil operated actions" was using the wrong term, so you reject examples of recoil being a force that causes things to happen. But it is and does, which is why any projectile thrower, from crossbow to rail gun, recoils. Using that recoil instead of gas pressure is why we have the term "recoi operation" instead of the term "locked breech blowback". 1911Tuner is trying to sell "locked breech blowback" as the correction for what people have understood to be "recoil" since at least 1896. They didn't get it wrong.

You have not been paying close enough attention. I believe no such thing. I’m the guy in the previous thread that defended the belief that recoil actions are recoil operated actions and not gas pressure operated blowback actions. My first post in this thread commented about using correct terminology and that short recoil is not the same as blowback. I know you are engaged in an intense dispute with 1911Tuner, but please pay attention to what the rest of us are saying that supports your argument.

Consider the following:
When a 150 grain projectile is accelerated up to 1000 fps, it creates the equivalent recoil momentum of accelerating a 1 lbs slide to 21 fps. (Mass x Velocity = Momentum) That means the slide will move 4 inches in 1/63 of a second at full speed. How is that not enough recoil energy to cycle a gun?

Does your math factor in the movement of the 1 pound slide being resisted by the recoil spring? I am not saying your wrong if the momentum equation says it will work, I just thought it would take more velocity to create sufficient momentum. Thanks for doing the math.

I was using examples that assumed nothing broke during firing. Not much point in discussing hypotheticals if the gun isn't strong enough. It is not hard to come up with examples of guns whose structural maximum chamber pressure is more than twice its operating pressure. Given that, the example works fine.

My comments in underlined italics.

 

[Nom de Forum]

45 auto is talkin bout plugging behind the powder charge. Tuner in front of it. I believe yall are so aggravated at each other you aint reading each other's posts!

Yup.

 

[Nom de Forum]

Perhaps this from my post in the original thread will be helpful:

Here is some information from a well known, authoritative and respected source, along with my comments in italics:

Blowback:

1. System of operation in self-loading and automatic weapons in which breech pressure overcomes inertia of the breech closure. (Note that there is no mention of movement of the barrel in this system. On most semiautomatic pistols the breech closure is the face of the slide.)

2. This system in its simplest form allows a totally unlocked breech and relies merely on the mass of the breech-block and the strength of the return spring to prevent the cartridge case from coming back too quickly after firing. (Note that there is no mention of movement of the barrel in this system, On most semiautomatic pistols the breech-block is the face of the slide. Examples of Blowback operated pistols are the PPK, Beretta 84, and many others chambered in .380, .32, .25)

Delayed Blowback:

Here as in the previous blowback systems the breech-block is not locked but some mechanical delay is incorporated to ensure that the breech-block cannot move back sufficiently rapidly to allow the unsupported cast to emerge from the chamber while the pressure is still high. (Note that there is no mention of movement of the barrel in this system. An examples of a Delayed Blowback pistol is are the roller delayed H&K P9S. The roller locked CZ52 is not, it is short recoil.)

Long Recoil:

In the long recoil system the bolt and barrel both recoil (together) a distance which is greater than the length of the unfired round. (Example: Hispano-Suiza 20mm cannon)

Short Recoil:

Here the breech-block remains locked to the barrel only while the pressure is high and in practice, as with a rifle calibre round, this involves a barrel travel of only a centimetre or so. The device locking the breech to the barrel is then released and the two components separated. (Note that the barrel is mentioned to be traveling as in moving in this system. Note that even in rifles using this system barrel movement distance is similar to that of Glocks and 1911s. Jane's entry on the 1911 specifies the method of operation as "short recoil, self-loading)


Does anyone still think the 1911 is a Delayed Blowback pistol? In the forty years since I first used a 1911, and never in National Match School, did I ever hear it described as anything other than a Short Recoil operated pistol.


Source of definitions for operating system types: Jane’s Infantry Weapons 1984-85

P.S. There is also a type of Blowback operation known as "Blowback with a locked breech" but it is not the same as the locked breech Short Recoil system.
Last edited by Nom de Forum; December 22, 2013 at 04:29 PM. Reason: Thank you RX-79G for your post #92 making it possible for me to correct the CZ52 error.


End of original post.

I have always known the 1911 and Glock are short recoil operated. I have never thought bullet friction was significant in their operation. Jane's is well respected for technical writing on weapons. Jane's had the opportunity to describe short recoil operation as technically a type of delayed blowback operation. Jane's did not with good reason.

 

[45_auto]

Does anyone still think the 1911 is a Delayed Blowback pistol?

LMAO!!!

Obviously you haven't read any of 1911tuner's posts .......

 

[RX-79G]

The blowback action does not immediately open upon application of chamber pressure. Not until pressure is sufficient to begin to overcome the inertia of the slide does the action “unlock”.

The pressure becomes sufficient to move the slide the same moment it becomes sufficient to move the bullet. When pressure converts to motion, both pieces that move do so simultaneously.

I don’t believe in your scenario that enough recoil will be generated to operate the action. You are implying making the Glock an electrically powered magnetic driver. The moment the “150 grain slug” leaves the barrel there is no remaining pressure. When a real Glock unlocks there is still remaining gas pressure on the face of the slide. I think you would have to greatly exceed 1000fps before this could be possible.

so you reject examples of recoil being a force that causes things to happen.

You have not been paying close enough attention. I believe no such thing. I’m the guy in the previous thread that defended the belief that recoil actions are recoil operated actions and not gas pressure operated blowback actions. My first post in this thread commented about using correct terminology and that short recoil is not the same as blowback. I know you are engaged in an intense dispute with 1911Tuner, but please pay attention to what the rest of us are saying that supports your argument.

Please don't let me put words in your mouth. It appeared that you said you didn't believe the reaction to the launch of a bullet alone would transmit enough energy to the slide to cycle it without gas pumping out the bore, and that is what I responded to. At this point, I can't tell whether you feel that a recoil operated pistol can function without also acting as a gas jet or not. The early quote suggests you feel it must be present, the second, correcting me, gives the opposite impression.

Does your math factor in the movement of the 1 pound slide being resisted by the recoil spring? I am not saying your wrong if the momentum equation says it will work, I just thought it would take more velocity to create sufficient momentum. Thanks for doing the math.

Considering that JohnKsa demonstrated that the slide begins moving before the bullet comes ouy, it appears that the velocity is created against spring pressure before gases exit the bore. But I did not factor the spring in my simple example.

 

[45_auto]

I think what you meant to say was that a recoil-type action can be designed around any type of propulsive system, which is certainly true....and in the same line of thinking, a blowback type action could be designed around any type as well (although it would be more challenging, in my opinion)

You do know the definition of a "blowback action", don't you? Notice the words ""expanding gases". How would you design a blowback propulsive system that DID NOT use expanding gases? By definition, it would NOT be a blowback if it used a different propulsive system.

http://en.wikipedia.org/wiki/Blowback_(firearms)

Blowback is a system of operation for self-loading firearms that obtains energy from the motion of the cartridge case as it is pushed to the rear by expanding gases created by the ignition of the propellant charge.

http://www.thefreedictionary.com/blowback

blowback

(Military) the action of a light automatic weapon in which the expanding gases of the propellant force back the bolt, thus reloading the weapon

As an example, a recoil operated 1911 type action could be easily adapted to any other type of propulsive system. Come up with a battery with the same energy density as gunpowder and every US military small arm will be a REAL "rail gun" (NOT something to hang a light on) within a couple of years.

Chemically powered Browning 1911 recoil action (I actually used a parallel link 1903 action instead of a tilting link 1911 action since it was easier to draw):



Electrically powered Browning 1911 recoil action:



You could simplify a Browning 1911 recoil action even further by eliminating the locking lugs since there would be no need to contain any pressure while the projectile is in the barrel:



We did some preliminary design on this DARPA rail gun back around 2005:

http://en.wikipedia.org/wiki/Railgun

It only takes a small nuclear reactor to run the thing.

 

[Nom de Forum]

RX79G , The guns we get in the shop blown up by squibb loads leaving a bullet in the bore (by squibb I mean primer with no powder)always have a ringed barrel, about an inch or so AHEAD if the chamber, where the second bullet hits the first. It seems to always blow out the bottom of the case in the throat area, along with the magazine, the grips and the shooters hand.
But my point is the primer almost always pushes the bullet an inch or two up the bore, so I think (I don't know for sure, I was wrong earlier on this thread) the increased pressures are due to a bore obstruction and not the bullet in the second round being pushed further into the case.
I DO know that tuners claim that he fired a 45 1911 with the bore obstructed so completely that the bullet could not move at all, resulted in no damage to the gun other that some hissing around the breech as the pressure slowly bled of; is most difficult to believe.

I have a barrel similar to what Tark described. It was brought to me by a novice handloader. The damage is a crack along the top of the barrel starting just a little past the chamber. Maybe I'll get motivated and learn how to post a photo to THR, but I am computer lazy and probably will not.

 

[RX-79G]

45auto,

I believe the point he's making is that you could also make a spring loaded or magnetic cartridge that would launch a bullet without gas that would cycle a blowback gun, so using a similar example of gasless function in a recoil gun doesn't prove anything.

And he has a point. The examples only started to come up when the welded breech came up. The definitions of these terms are concrete enough, but some of the misunderstandings could only be addressed with examples of what isn't happening

 

[RX-79G]

Tark,

I just realized what is going on with those guns you mentioned - they've started to unlock, but with trapped pressure.

When the round behind the squib was set off, it came out of the casing and either pushed the squib down the bore, or just found it a bit down the bore.

Since the new round did move, it generated recoil, which got the slide moving (as in JohnKSa's video). When the bullet impacted the squib the slide didn't necessarily stop and must have gotten far enough back to link down to unlock. It then unlocked with a casing and maybe a half inch of bore full of pressurized gas. The breech then opened and the case blew itself out of the bore far enough to blow out by the feed ramp. Very similar to the Glock out of battery thing we discussed on TFL, except this one started in battery and recoiled to unlock without moving the bullet out of the barrel.

In the case of Jim K's experiment, the bullet was not allowed to move at all in the barrel. Since it didn't move, it generated zero recoil so the slide didn't move either. That kept the pressure in the chamber.

 

[Nom de Forum]

LMAO!!!

Obviously you haven't read any of 1911tuner's posts .......[/QUOTE

That was a rhetorical question in the original short recoil thread in what now seems like a thousand years ago. I have read all his posts and I do wonder if he fully accepts that the 1911 is not technically a delayed blowback. That is why I re-posted the information here hoping the gravitas of Jane's would end all doubt.

 

[Nom de Forum]

Here is something to lighten things up a bit:

Can anyone name a short recoil operated pistol that is not a self-loading pistol?

I can.

 

[RX-79G]

Short recoil, no. But a Mateba auto revolver is not "autoloading" in some sense.