How much power is lost by S/A Marlins .22lr


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ivanthehunter
January 18, 2009, 01:03 PM
Power loss of 22lr ammo when cycling the action of a marlin when compared to that of a bolt action.

I have heard reports that claim a 1/4 loss of power but that seems crazy.
I don't have a chronograph to measure the muzzle velocity of my semi auto and even compare that to the velocity stated on the ammo box.

Can any one shed any info on this.

Thanks Lads

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John828
January 18, 2009, 01:19 PM
Less power loss than you get when you shoot Remington bulk pack. Ever notice how some rounds are quieter than others? The minute discrepancies in powder charge makes big differences on the chrony.

It never occurred to me that a semi-auto cycling would siphon off some of a load's power and velocity, but if it does, it would be a very, very small amount.

ArmedBear
January 18, 2009, 01:20 PM
Good question.

I wish I knew the answer. I have to get a chronograph and compare. In fact, that might be the first thing I do, when I finally get one someday.:)

However, I don't believe we're looking at all that much, definitely not 1/4 of the velocity or anything.

ArmedBear
January 18, 2009, 01:25 PM
It never occurred to me that a semi-auto cycling would siphon off some of a load's power and velocity

You have to consider that a .22 does not have a bolt lock. It's just a bolt on a spring.

An AR-15 remains locked shut until the bullet passes the gas port and the gas pulse has traveled back down the gas tube. Therefore, there's no pressure loss at all until the bullet is near the muzzle.

With a .22 blowback design, you can start to get some pressure loss sooner. I believe it happens as soon as the pressure drops below the point where the case is held against the chamber walls (obturation), but I could be mistaken.

A .22 blowback is such a completely hokey design that it's a wonder it works at all, to say nothing of having really good reliability (at least in the better-designed guns, like Ruger .22 pistols).

CajunBass
January 18, 2009, 01:32 PM
None. The bullet has cleared the barrel by the time the breachblock starts to move backwards under recoil.

Picher
January 18, 2009, 01:33 PM
The amount of energy and velocity loss is so little that it's insignificant. I haven't noticed that bolt action or semi-auto bullets both strike with about the same drop at 100 yards when both are sighted in at 50 yards.

Remember two things:

1. The maximum velocity of a .22LR is reached in the first 16 inches of barrel.

2. The cartridge case does not move until pressure reduces to the point that the case doesn't bulge when it exits the chamber. If it exited when there was full pressure, it would bulge and perhaps burst.

Picher

rangerruck
January 18, 2009, 02:13 PM
none is correct; lets do a little mental expirement here. take a round, and shove it down, in the end of your muzzle, not more than say 1/4 of an inch. Leave it there. go and chamber a live round, and pull the trigger. What would happen? because of the intrusion in the end of the bbl, all the bolt stuff will explode backward into your facial area. Why? because the bullet has not yet cleared the end of the bbl, and is now acting as a stuck round, causing way too much backward gas pressure/expansion.
now then, try the same thing, with a clear bbl, and chamber and fire a live round. bolt just cycles. Why? becuase the bolt does not start to unlock and move rearward, until the bullet is at the end, leaving the muzzle.

So semi's are designed to work, to unlock the bolt, as the bullet leaves the muzzle, otherwise, the gas pressure would be far too great, if the bullet were still traveling down the bbl, and the bolt started to unlock, the rearward pressure would be damaging to the rifle and the shooter.

Mike U.
January 19, 2009, 04:27 AM
none is correct; lets do a little mental expirement here. take a round, and shove it down, in the end of your muzzle, not more than say 1/4 of an inch. Leave it there. go and chamber a live round, and pull the trigger. What would happen? because of the intrusion in the end of the bbl, all the bolt stuff will explode backward into your facial area. Why? because the bullet has not yet cleared the end of the bbl, and is now acting as a stuck round, causing way too much backward gas pressure/expansion.
now then, try the same thing, with a clear bbl, and chamber and fire a live round. bolt just cycles. Why? becuase the bolt does not start to unlock and move rearward, until the bullet is at the end, leaving the muzzle.

Ya probably wanna start this little exercise in stupidity with the cleared barrel first.

Also, please videotape it. It'd make one a slam dunk for a Darwin Award. :D

wayne in boca
January 19, 2009, 04:38 AM
I'm not sure that it's possible to videotape a mental experiment.If it is,I'm going into the porn industry.:)

Mike U.
January 19, 2009, 04:05 PM
Ahhh, what fun would it be as a mental exercise? Your right, it wouldn't be possible to videotape a mental experiment, plus it wouldn't make for a very good video. Drat...

rcmodel
January 19, 2009, 04:35 PM
None. The bullet has cleared the barrel by the time the breachblock starts to move backwards under recoil.Give the man a cigar for being the first with the correct answer!

rc

rangerruck
January 20, 2009, 11:05 AM
cigars, and toilet paper for all my friends!!!! Go to youtube, and look for a slow motion fire , of a ar and a ak rifle, you will see it happen. bolt does not start to open up, until the round clears the tube...

ArmedBear
January 20, 2009, 11:12 AM
semi's are designed to work, to unlock the bolt

The Marlin 60, Ruger 10/22, and other .22 semiautos do NOT unlock the bolt, because the bolt DOESN'T lock. See my post above.:)

Go to youtube, and look for a slow motion fire , of a ar and a ak rifle

rangerruck -- I'm sorry, but this is utterly irrelevant to the question.

These are gas-operated, locking-bolt action designs, bearing essentially no relation, functionally, to the actions in question. See my post above. They also incorporate a delay, since it takes a finite amount of time for the pressure pulse to travel from the port, back down the gas tube. Neither a bolt loc, nor a gas tube, exists in the rifle designs we're discussing.

The OP asked about blowback rimfires with relatively long barrels. I do not know when the bolt begins to move rearward. I do believe that obturation by the brass is the only de facto form of "locking" in a simple blowback design.

I would guess that it may start to move back before the bullet has left the barrel, once the pressure has dropped below X. I just don't know what X is, and when X occurs.:)

Anyone know about the engineering of a blowback rimfire?

Shear_stress
January 20, 2009, 11:19 AM
Go to youtube, and look for a slow motion fire , of a ar and a ak rifle, you will see it happen. bolt does not start to open up, until the round clears the tube...

That's because in an AK or AR the action is locked until combustion gases reach the gas port and start to bear on the piston or bolt carrier, respectively--and both the piston or bolt carrier start moving backward as soon as this happens. Just like in a 1911 pistol, the piston or bolt carrier allow a small degree of backward motion *before* they cam open the bolt. If you look at an AK bolt carrier, you'll see a little gap between the back of the bolt lug and the bolt carrier. This is what allows the bolt carrier to move directly backward for an 1/8" or so before it turns the bolt. This gives the bullet enough time to escape the muzzle.

This is absolutely not the case in a blowback .22lr. As ArmedBear has pointed out, the blowback action is *not* locked. If the bolt (or the entire rifle for the brief period of case obturation) didn't start moving in a blowback, neither would the bullet. There's no getting around Newton here.

ArmedBear
January 20, 2009, 11:31 AM
Small addendum: X being the pressure required to "inflate" the brass and keep it stuck in the chamber.

Shear_stress
January 20, 2009, 11:38 AM
The thing to remember in a blowback is that the bolt is much heavier than the bullet and will move backward a lot slower than the bullet travels forward. In many blowback actions, there may be even be a point where a small portion of the rear of the case is actually outside the chamber before chamber pressure has dropped to zero. This is one of several reasons why blowback actions are limited to relatively low pressure cartridges.

In fact the Remington Model 51 .380 pistol used an action that *required* the case to recoil out of the chamber a small distance before locking.

rcmodel
January 20, 2009, 12:32 PM
The thing to remember in a blowback is that the bolt is much heavier than the bullet and will move backward a lot slower than the bullet travels forward.You get a cigar too!

rc

czarjl
January 20, 2009, 01:36 PM
I think that could be tested if you were able to “lock” a bolt on semi-auto rifle in the forward position and fire it, measuring the bullets exit velocity. Then with the same rifle let it cycle when fired and measure the bullets velocity again. Assuming the rounds are exactly the same and no other differences in powder, primer, bullet weight and case weight (most plausible way to do this is fire many rounds and average there readings). A difference in velocity would mean a loss of power.
The other thing to do is to film the action and muzzle at the same time with a high speed camera to see if the bolt is moving back in relation to the bullet exiting the muzzle.

My prediction would be that there is a very slight loss of power due to the cycling of the action. The loss of some of the energy to moving the bolt back at the same time the bullet is moving forward (the bullet does not have the solid “push off” of a fixed bolt).
I believe that the bolt starts moving back before the bullet exits the muzzle (if it didn’t the pressure from the powder would be gone). In a theoretical scenario the bolt starts moving back at the same time the bullet starts moving forward (if we ignore things like friction and the case expanding) . The bolt is heavier than the bullet and will therefore move much slower (F=m*a, Newton’s Second law)

Now I just need to convince my wife that I need to buy a good chronograph and to spend the weekend at the range testing this.

CajunBass
January 20, 2009, 02:12 PM
Not only is the bolt on a 22 semi action heavier than the bullet, there is a recoil spring that has to be overcome in the process of driving the bolt back. Between the weight of the bolt, and that spring, the much lighter bullet is long gone before the bolt moves. The pressure has nothing to do with it. It's blowback, not gas operated. Once the bolt has reached the end of it's rearward travel, that same recoil spring now pushes the bolt forward where it picks up the next round in the magazine and pushes it into the chamber as the bolt returns to batter.

Hi-Points, which are also blowback operation, work the same way. That's why they have such massive slides and strong recoil springs.

Funderb
January 20, 2009, 02:16 PM
the reason it works is because the bolt is simply much heavier than the round leaving the barrel. The bolt starts moving fairly quickly, but the round leaves the barrel before the shell clears the chamber.

ArmedBear
January 20, 2009, 02:21 PM
Between the weight of the bolt, and that spring, the much lighter bullet is long gone before the bolt moves.

There's nothing about the weight of the bolt or the tension of the spring that would keep the bolt from moving before the bullet is gone. Since the whole mechanism is lubed, there's only a little static friction to overcome, which means that the bolt would start moving essentially as soon as the bullet does. Every action has an equal and opposite reaction.

The pressure has nothing to do with it.

Yes it does. It keeps the brass stuck in the chamber while the pressure is high enough. It's also the reason that reloading procedures require cleaning the case lube off the brass before using the rounds: lubed cases slide back and put excess pressure on the bolt face or the frame of a revolver, while clean cases expand into the chamber and stick in place during peak pressure (obturation).

the round leaves the barrel before the shell clears the chamber

Funderb has it.

However, that doesn't answer the original question. The shell may not be clear of the chamber, but there still may be pressure lost, if only because the moving shell enlarges the volume in which the powder expands. In reality, there's also some leakage, I think.

How much, and exactly when and where during the bullet's travel down the barrel determines the velocity lost due to the action.

And this is what we still haven't found out.:)

Ratshooter
January 20, 2009, 02:46 PM
No one ever mentions it but the hammer also holds the bolt in the closed position.

Try this, take a Ruger 22 auto that has been fired and has the hammer at rest against the bolt. Pull the bolt back. Did you feel how much initial resistance there was? Now do the same thing with the hammer cocked. There is a difference isn't there.

The hammer pressure is part of the design and has a bearing on how heavy the bolt spring needs to be. Thats why I am not a fan of lighter hammer springs in semi-auto 22s.

And yes the bullet is long gone before the action opens.

rcmodel
January 20, 2009, 02:51 PM
Someone with a semi-auto .22 and a chrono needs to measure it.

You can easily hold the bolt closed on a .22RF with your bare hand on the bolt handle.

Hey wait! Thats it! Yea!
Thats the ticket!

Anytime you need more power, just hold the bolt closed!

Just don't expect to see any differance, cause there won't be any.

rc

Funderb
January 20, 2009, 05:14 PM
I wish i had some device for measuring the pressure gradients, if I could invent it.....


but there would logically HAVE to be some loss of energy in a semi-automatic that runs on straight blowback. Think about it, the amount of energy that is used to run the bolt in a semi has to come from somewhere. It might not be very much compared to the energy delivered to the bullet, but it just as well exists.

Unless you want to say that that energy is just turned into the slightly higher recoil of the bolt action.

I methinks there would be energy loss, and there is.

rangerruck
January 20, 2009, 11:10 PM
I still say, that there is too much resistance to overcome, and that the bullet is at the muzzle, or gone from the tube, before the bolt moves back. Lets look at what it has to overcome first, before it starts moving back.
Case expansion, then case retraction, weight of bolt assy., operating rod friction, op rod spring, gravity of bolt, and friction of bolt, sliding on bottom and side rails, hammer, or sear setup. All this has to be overcome, before it starts moving backwards, and I am sure this is not all, I'm just not that smart.

Kurt_D
January 20, 2009, 11:31 PM
God I wish I remembered the name of the article but YES you do lose some velocity with the semi 22 vs. bolt action. Test was done with 2 Marlins, I beleive, one semi and one bolt with the same barrel lenght. Semi averaged about 20 fps slower than the bolt; not enough to worry about.

elmerfudd
January 20, 2009, 11:50 PM
A .22 blowback is such a completely hokey design that it's a wonder it works at all, to say nothing of having really good reliability (at least in the better-designed guns, like Ruger .22 pistols).

I can't say I've ever seen a .22 semi with really good reliability, although Marlin model 60's probably come close. I think it's just a problem of a very short, rimmed cartridge. They just don't do very well when they're stacked on top of each other.

WNTFW
January 20, 2009, 11:55 PM
RCModel is now selling the "Overdrive Kit" for all .22LR Semi Auto's.
The instruction manual will contain several "Mental Images"
Left handed model is still in testing phase.

"Not enough to worry about" Agreed, I got bigger problems! The Rem bulk packs are a roll of the dice at farther ranges for sure.

elmerfudd
January 20, 2009, 11:56 PM
As far as the bullet clearing the barrel before the bolt starts to move backwards, I just don't think that stands up to reason. You can cut the barrel on a 10/22 down to just a couple of inches and they will still cycle. If the bolt weren't beginning to cycle until it had cleared a standard 18.5" barrel, then imagine the situation with a 6" barrel. By the time the bullet has left the 6" barrel and traveled another foot there would be no pressure left to cycle the action, yet chopped down 10/22 pistols and SBR's still do function.

saturno_v
January 21, 2009, 01:28 AM
I always knew that one of the advantages of the blowback design is that you have virtually no power loss compared to a gas system.

In a blowback firearm, bolt and bullet start moving at exactly the same time once you fire....there is no way around physics.

However, to keep things working and avoid a nice burst of hot gases in the shooter's face the bolt has to be much much more heavy than the bullet and calibrated to the cartridge performance as well, one of the reason that the blowback system is usually limited up to cartridges in the same power class as the 380 Auto.

If you want to keep using the blowback architecture with more powerful rounds you have two choices:

1) Some sort of delayed mechanism (typical example the rollers in the CETME semi auto assault rifle in 7,62 X 51 NATO and civilian versions in 308 Winchester) to supplement the "natural" cycle delaying action offered by the temporary bulging under pressure of the case walls against the chamber

2) a very very big and heavy mass for your bolt...ever wondered why Hi-Point pistols are so big, unwieldy, heavy and ugly??? Because they use a blowback system for full power pistol rounds (9 mm, 40 S&W and 45 ACP) so they need an oversize slide mass.

So, as we said, the much heavier bolt start moving at the same time as the bullet.
However, because its sheer mass, the recoil spring and the pressure that keeps the case walls tight against the chamber walls, the bolt moves with a velocity which is a minimal fraction compared to the speed of the bullet.
To be fair and precise, the bullet, despite being very light, has to win the friction of the rifling which increases in a non linear fascion as the speed increases, a problem that our lubricated bolt doesn't have.
In practice when the bullet start leaving the muzzle, the bolt has yes moved backward but not in an amount which allows noticeable gas escape and we still have the bulged case walls from the pressure which form some sort of a gas seal with the chamber.
With the bullet out the pressure drops and the case walls "retreat" from their pressure against the chamber..the bolt (and the recoil spring), because of its sizeable mass has acquired enough momentum to complete the cycle and lo longer has to "fight" the bulged case under pressure.

As you may suspect, one of the critical aspect of a blowback design reliability is the use of good quality cases and carefully refined chamber tolerances.

A well designed and calibrated blowback system is insensitive to barrel lenght for a given caliber.


Interesting enough, in the artillery field, where the aestethical appearance and weight is not a factor, the blowback design is being used....these are really big guns :D:D:D

czarjl
January 21, 2009, 11:17 AM
That makes sense to me and explained better than I could have.

waterhouse
January 21, 2009, 11:42 AM
Test was done with 2 Marlins, I beleive, one semi and one bolt with the same barrel lenght. Semi averaged about 20 fps slower than the bolt; not enough to worry about.

Not a very conclusive test. You could probably find 2 bolt action marlins with the same barrel length that showed a 20 fps average difference between each other.

I'm not saying that test results aren't valid, but the only way I can think of to prove the theory is to use the same exact barrel with both action types.

Thanks to the OP for bringing the topic up, interesting question and I certainly have learned a bit about the blow backs.

ArmedBear
January 21, 2009, 12:05 PM
I can't say I've ever seen a .22 semi with really good reliability

I have many, many thousands of rounds through a Ruger 22/45 and more recently a Mark II with zero FTF on anything but dud ammo.

Dr. Tad Hussein Winslow
January 21, 2009, 01:11 PM
I don't think ANY; and surely not much. The bullet has already left the muzzle before the the casing clears the chamber mouth, IINM. Who's gonna do the controlled experiment, though?

The Rem 552 speedmaster is very very reliable.

rcmodel
January 21, 2009, 01:23 PM
Test was done with 2 Marlins, I beleive, one semi and one bolt with the same barrel lenght. Semi averaged about 20 fps slower than the bolt; not enough to worry about.Totally invalid test.

Any two barrels, even installed on the same receiver, could easily have more velocity variation then that.

But comparing two different rifles, off two different production lines, and built months or years apart?

No way the test means anything at all, except one rifle had a "faster" barrel then the other.

rc

Funderb
January 21, 2009, 01:59 PM
Come on, guys, you are ignoring physics here, there HAS to be an energy loss, because energy is being diverted to operate the bolt. There is no way on earth or in heaven that there is no energy loss from the bullet involved in this process.

Vern Humphrey
January 21, 2009, 02:04 PM
Try this experiment. Shoot your Ruger automatic, 10/22, or whatever and pick up the fired case. Try to put it back in the chamber.

If there was any significant gas pressure remaining when the breech block started back, the fired case would be swollen and would not fit.

Pressure doesn't get that low until the bullet is gone.

czarjl
January 21, 2009, 03:32 PM
I still like my test idea of using a semi-auto with the bolt locked and then letting it cycle. If there is a measureable difference this should show it… I think it will be a few Feet per second but not much in the grand schema of things.

saturno_v
January 21, 2009, 03:37 PM
Come on, guys, you are ignoring physics here, there HAS to be an energy loss, because energy is being diverted to operate the bolt. There is no way on earth or in heaven that there is no energy loss from the bullet involved in this process.

Whatever energy loss you may have because of the bolt going backward is totally negligible and hardly measurable with our home grade equipment (Chrono)

This hypothetical "loss" is way way less than a gas operated system firing the same cartridge with the same barrel.

Vern Humphrey
January 21, 2009, 03:49 PM
Come on, guys, you are ignoring physics here, there HAS to be an energy loss, because energy is being diverted to operate the bolt. There is no way on earth or in heaven that there is no energy loss from the bullet involved in this process.

If it were done with a bolt action rifle, energy would be "diverted" to move the bolt. In fact, energy (actually momentum) would be "diverted" to move the whole gun.

As I said, fire your semi-auto blowback .22, pick up the case and see if it will go back into the chamber -- if it's swelled or blown out to the point that you can't get it back in, that will indicate high pressure after the bolt started moving.

But if it slips back in like it came out, then clearly there was very little pressure at the time of extraction, and hence the bullet was gone before the bolt opened.

Dr. Tad Hussein Winslow
January 21, 2009, 04:50 PM
I'm not saying that test results aren't valid, but the only way I can think of to prove the theory is to use the same exact barrel with both action types.

Or like someone said, using the same semi-auto rifle, just manually holding the bolt closed with the bolt handle in the second part of the test. Shoot 10 rounds each way; average them - who can do it this weekend and has a chrony? :)

Vern Humphrey
January 21, 2009, 05:01 PM
I've done it -- or something close.

I shot a .22 pistol (in this case an M1911 with a Ciener conversion kit) both as-is, and with lead weights clamped to the slide -- to the point where the slide no longer cycled.

The results were that 30-round strings fired with the basic pistol, with a 1-lb weight, a 2-lb weight, and a 5-lb weight were statistically the same.

gvnwst
January 21, 2009, 05:31 PM
However, to keep things working and avoid a nice burst of hot gases in the shooter's face the bolt has to be much much more heavy than the bullet and calibrated to the cartridge performance as well, one of the reason that the blowback system is usually limited up to cartridges in the same power class as the 380 Auto.


Okay, this is coming with the knowledge that i know very little about pistols, but aren't almost all pistols blowback? The 1911, glock, SA XD, H&K USP, ect? I have always read about them being this...they don't use a gas system, that is for sure.

Other than that, they are right, while the bolt does move back at firing, by the time it goes anywhere far (more than a few thousandths of a inch) the bullet is gone out of the barrel. There is no power loss, because the energy is simply put into making the bolt go back faster than the gun normally would, and the gun just goes back a bit less.

rcmodel
January 21, 2009, 05:37 PM
All semi-auto .22 RF pistols & rifles, and most all .25, .32, and .380 ACP pistols are blow-back operated. In other words, at no time is the slide or bolt connected to the barrel.

Almost all center-fire pistols are Browning locked-breach, short-recoil operated.
The slide & barrel are locked together long enough for the bullet to clear the barrel and pressure to drop to near nothing.

rc

Vern Humphrey
January 21, 2009, 05:43 PM
Okay, this is coming with the knowledge that i know very little about pistols, but aren't almost all pistols blowback? The 1911, glock, SA XD, H&K USP, ect? I have always read about them being this...they don't use a gas system, that is for sure.

No. Most centerfire pistols are locked-breech, short recoil actions.

The classic is the M1911. The barrel is locked to the slide (which includes the breech) by horizontal lugs which mate with transverse grooves in the slide. When the gun is fired, the barrel and slide recoil as a unit.

There is a swinging link on the bottom of the barrel, near the breech, and a pin (the slide stop pin) runs through the frame of the pistol and through the link. As slide and barrel continue backward, the link pulls the rear end of the barrel down and out of engagement, and brings the barrel to a stop. The slide continues rearward, extracting and ejecting the case and over-riding the hammer to re-cock the gun.

The recoil spring, which has been compressed by the slide coming back, now expands and drives the slide forward. The slide strips a fresh cartridge out of the magzine, chambers it, and hits the breech.

At this point barrel and slide continue forward, and the link forces the barrel up so the lugs re-engage the grooves.

saturno_v
January 21, 2009, 05:45 PM
Vern

You nailed it perfectly....even in a bolt action rifle the bolt is "moved" backward....the entire rifle is moved backward for that matter because the bolt is locked in place....this is one of the reason that the recoil of a semi-auto rifle is milder compared to a bolt action chambered in the same caliber.

The only hypothetical insignificant energy loss I was talking about and that I can imagine on a blowback system is the extremely minuscole increase in the chamber volume created by the beginning of the backward movement of the bolt as the bullet proceed through the barrel compared to exactly the same barrel on a bolt action rifle (same charge acting on a bigger volume = less pressure).
On top of that whatever little gas can escape from the seal formed by the bulged case under pressure.

But this "loss" is absolutely and totally insignificant, other factors such as the outside temperature, bore tolerances, barrel temperature, rifling design, etc... have a much much more bigger impact on performance.

Comparing the muzzle velocity of a blowback semi auto 22 LR rifle with an other 22 bolt action of the same barrel length is absolutely without merit. Any meaningful and measurable velocity differences are due to the other factors already mentioned...the same rifle can have much more than 20 fps of differences between shots during the same session

saturno_v
January 21, 2009, 05:48 PM
gvnwst


Vern explained for you.

This is the reason why locked-breech semi auto pistol in full power caliber do not need huge and heavy slides.

gvnwst
January 21, 2009, 05:50 PM
Hmm...this is intresting. I was shooting a 1911 for my first time on sunday (yay!) and i didn't notice tha barrel move at all. Cool.

rcmodel and Vern, thanks for the explanation.

Vern Humphrey
January 21, 2009, 05:58 PM
Take that .45, being very sure it's unloaded, and wrap your strong hand around the grip, and use your weak hand to move the slide slightly backward, a quarter of an inch or so, while you look at the breech. You will see it drop down as you press the slide back.

saturno_v
January 21, 2009, 06:09 PM
gvnwst

Take your 1911, make sure it's unloaded and pull back the slide very very slowly and you will notice that at the beginning, for a very short distance, barrel and slide go back together....if you keep pulling back at some point the barrel will stop going backward and it is pulled down while the slide keep going back.

If you have or you can put your hands on a small semi-auto in .380 or less do the same thing (make sure it's unloaded) and you will notice that the barrel will not move back at all.

gvnwst
January 21, 2009, 06:22 PM
Unfortunatly, it is not my 1911, i have no centerfire pistol as of yet. (one reason i know so little about them) It is a freinds who i see very little. Nest time i will be sure to do that though. I do have a .22lr pistol though.....

JustsayMo
January 21, 2009, 06:22 PM
I don't have a 16" bolt gun so I used a lever gun.

All 16" barrels Federal Bulk ammo Average
Marlin Mountie TDS 1251 fps average
Marlin Papoose 1180 fps average
Ruger 10/22 1187 fps average

FWIW: longer barrels in bolts and levers do produce higher velocities with most standard and high velocity 22lr Ammo. My 24" Remington and Marlins will typically get 25-100 fps more than the 16" barreled rifles depending on the ammo. The hotter the ammo the greater the gap percentage. The 16" barrels typically shoot CCI CB longs faster ~ 1000 fps vs. 900. CB longs are also a lot louder out of the shorter barrel compared to the 24" barrel where the hammer falling and the target impact are louder than the report.

ivanthehunter
January 25, 2009, 08:06 AM
Some great food for thought here:)
i believe that the only way to do this test is to some how shore up the slide to make a s/a into b/a and to run several rounds through the chronography.

Some posters suggested that a person might be able to hold the slide closed via the slide bolt/finger-griper but i think that this might be fool hardy to say the least and also this would not be perfectly reproducible each time to the same standard.

Also if these little Marlin 70PPS 22lr's are designed to function on high velocity then the weight of the slide block in conjunction with the pressure of the cocking spring and the slide spring have all been calculated and tweaked to make the system work for that ammo. If i placed a CCI Stinger (hyper velocity) in the chamber then the theoretical loss would be much larger % of the available power.

Its as good a reason as any why manufactures should produce a hybrid S/A-B/A as these blowback S/A's are tuned to work with the best consistency with high velocity ammo. However i have noted that although these S/A'S will fire both subs and hyper ammo that the high power gives very erratic groups and the subs are quite good.

These hyper ammo groups are crazy both in the windage and in elevation, leading me to suspect more than irregular loads at the factory. It seems that the hyper ammo forces the slide back(enough to through the balance out) before the bullet has left the barrel and hence the super erritic groups..

JustsayMo
January 25, 2009, 09:04 AM
Ivanthehunter wrote: "These hyper ammo groups are crazy both in the windage and in elevation, leading me to suspect more than irregular loads at the factory. It seems that the hyper ammo forces the slide back(enough to through the balance out) before the bullet has left the barrel and hence the super erritic groups.."

Many manually operated bolt rifles suffer poor accuracy from hyper-velocity ammo too. Other factors are probably at play here too including rifling twist rates.

In my experience the gain in velocity and the supposed improvement in on game performance (dead is dead) does not make up for the loss in accuracy. Impressive numbers on the chronograph have little effect when the target is missed. When it comes to hunting I've found is that when the bullet capable of penetrating the vitals is placed where it is supposed to go, it does the job.

moooose102
January 25, 2009, 09:10 AM
None. The bullet has cleared the barrel by the time the breachblock starts to move backwards under recoil.

that is my opinion also. on larger rifles, the breach actually stays locked, but i am not sure how this works on blowback models. i do know that really, the bullet IS out of the barrel before the cartridge case clears the chamber, or there would be hot gasses being spit all over the place!

ivanthehunter
January 25, 2009, 11:49 AM
when I've shot stingers at night time out of this S/A i have been hit in the face with red hot sparks shooting out of the breach--some time but not all the time!


Really I'm starting to think that among 22lr shooters there is a real market for a S/A with a lockable breach that simulates a B/A locked breach.This type of firearm would be S/A with one type of ammo (normal High Velocity) and could be breach locked and manually cycled for other types giving a shooter more scope and hence more use out of the many types of ammo that are currently available today..

Anyway now to source a good deal on a chronograph....

PS any thoughts on manually holding the breach closed with fingers:uhoh:

There were 3 of these
Krico 260 EA--German
Springfield 87A
Walter in early 1930's
All were S/A-B/A hybrids

rcmodel
January 25, 2009, 01:07 PM
i think that this might be fool hardy to say the least and also this would not be perfectly reproducible each time to the same standard.If you haven't tried it, don't knock it!

You can easily hold the bolt or slide shut on a .22 with one thumb or finger.

rc

Vern Humphrey
January 25, 2009, 03:08 PM
i believe that the only way to do this test is to some how shore up the slide to make a s/a into b/a and to run several rounds through the chronography.
I did that by clamping lead weights to the slide of a M1911 with Ciener Conversion Kit.

No difference between the free-running slide, and a slide with so much weight it won't come back at all.

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