Blowback 22 long rifle conundrum

S

stubbicatt

New member
I have an acquaintance with several sections of land infested with prairie dogs. We used to go out and shoot them out to about 200 yards or so with 22 long rifle cartridges. It's certainly cheaper than 223 or similar dedicated varmint cartridges, and once one calibrates his eyeballs to determining distances one can be remarkably consistent in hitting the little dudes with a rimfire. At 200 to 600 whip out the poodle poppers in 223 caliber.

Anyways, he said to me he always uses his bolt actioned 22 rifle in this application, as a semi auto gives up some velocity due to the energy diverted to work the blowback action. At the time I kept my mouth shut, *knowing* as I did then that this was just not true, that blowbacks divert the energy of *recoil* not bullet velocity, and that the action doesn't open until the bullet has departed the muzzle, well downrange, and that the action type would not affect velocity.

Now? Now, I'm not so sure anymore.

What say ye?
 
If the bullet hits the target, why does it matter what got it there?
An accurate auto loader could be very handy sometimes when those little rodents duck and dodge.
 
Long ago, I had time to shoot pests beyond 100m with a .22. I used a Brno 4 with a 28 inch barrel; my guess is that I was getting a lower velocity from that than a 10/22 with a 16 inch barrel. I used both subsonic and faster stuff, and can confirm that the difference in velocity does provide a very different POI.

Velocity isn't the real problem though. At 200m, the bullet will have dropped something like five feet and the rate of drop at that point makes precisde ranging necessary. If I ever hit a squirrel sized pest at that distance with that kind of drop, I would be forced to call it a happy accident.

I've hit squirrels with Aguila colibri from 25 feet, and note that it isn't even close to lethal. I wouldn't expect a .22lr to have much more oomph than that at 200 yards.
 
You guys are missing the Terminus Downhillus Affect (TDA)

As anyone who has coasted a car should know, the steeper the hill the faster you coast (my wife set a world record of over 95 mph scaring the you know what out of me in BC!)

the upshot (well actually downs shot ) is that as the 22 has such little velocity to start with, to get out at 200 yds you have to aim the mentioned 5 feet high.

As the bullet hits the top of the arch (top of the hill) it then GAINS speed as its going down a steep downhill there by re-acquiring velocity and smiting the little buggers with close to biblical force.

All vey easily undersott3on once you think about it. Best done under the influence of alcohol or drugs though (the thinking part)
 
You guys are missing the Terminus Downhillus Affect (TDA)???

No, I believe it's the 22lr terminal warp corollary, which states that at the point at which a 22lr projectile begins to reach its maximum velocity versus apex the forces of physics cause the projectile to bend the space time continuum and allow the 22lr to achieve speeds and vectors at ranges beyond the capacity of rimfire propulsion.

This is the cause for terminal shots on game at ranges beyond 200 yrds. I think I missed something for windage, but that's just nitpicking. :D
 
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There appears to be some instability in the time-space continuum.

Back to the original question, I knew someone who actually tested to see if he could determine the velocity loss out of a semi-auto versus a bolt action. If I remember correctly, he figured it was less than 20 fps. Yes, there is a velocity loss (because it takes energy to cycle the action and the energy has to come from somewhere), but it's probably less than the variation from shot to shot.
 
There was a gunzine writer who shot a Ruger Mk I with the bolt clamped shut and then operating normally.
Function in blowback gave HIGHER velocity.
 
"that blowbacks divert the energy of *recoil* not bullet velocity, and that the action doesn't open until the bullet has departed the muzzle, well downrange,"

Well, you're partially correct. Blowback DOES NOT USE RECOIL energy to operate the action. Blowback uses residual gas in the bore to operate. Recoil operated actions operate on inertial energy contained in the mechanism after the shot is fired and this energy would be insufficient in a low recoil cartridge like 22LR.
The difference in bullet velocity(and resulting energy) between semi-auto and bolt action is likely within the normal variation in performance within different firearms so is of little consequence in actual field use. Now, if the bolt action has a longer barrel, then of course, there might be a noticeable difference.
 
That test was interesting and surprising.
The semi auto was faster.....but only by 3 and 5 fps in the two different brands of ammo. Same rifle used so what can you say .... All those who think a semi auto uses up energy operating the bolt haven't seen this test.

The surprising thing is , it really doesn't matter , velocity wise, if you shoot a semi-auto or a bolt action....in 22 LR anyway. It doesn't seem logical, but the test proved the point as well as could be demonstrated..

Thanks for posting
Gary
 
Sorry, but blowback guns are operated by the gas generated by the burning powder, not by recoil. But the breech (bolt) is kept closed by its own inertia until the bullet has left the barrel, so no pressure is lost.

Most modern locked breech auto pistols do operate by recoil; the force of the bullet moving forward causes recoil, which causes the barrel and slide to move back as a unit until unlocked by a cam or link. If the bullet doesn't (can't) move, the gun will not function.

FWIW, the bolt of a Ruger does not need to be clamped to keep it closed; it is easy to hold closed with the off hand.

Jim
 
James K said:
blowback guns are operated by the gas generated by the burning powder, not by recoil.
[...]
Most modern locked breech auto pistols do operate by recoil; the force of the bullet moving forward causes recoil
Click to expand...
I have a few questions: First, why does recoil operate a locked breech system but not a blowback? How is it that recoil is a factor in one and not the other? Also, how do we know this is the case?

I'm not disagreeing with anything here, I'm just trying to understand it better.
 
"I have a few questions: First, why does recoil operate a locked breech system but not a blowback? How is it that recoil is a factor in one and not the other? "

I will attempt to give a simple explanation w/o going into too much detail.

Recoil operated designs usually allow the barrel/slide to "move" together under recoil retarded by the weight of the moving parts and the recoil spring. This allows gas pressure to drop before the breech "unlocks" from the barrel meaning the system can handle higher pressure rounds. This design has been used in shotguns, rifles, handguns, and full auto firearms.
Blow back is often used in low pressure/low power firearms (like the 22LR) but has been used on more powerful weapons such as 9mm/45 ACP sub machine guns and handguns that have the barrel "fixed" to the frame. The fly in the butter when used in higher pressure/power firearms is the requirement for heavier slides/reciprocating bolts and/or recoil springs to increase the inertia of those moving parts in order to resist initial movement of the bolt/slide.
If more detail is desired, google is your friend.
 
Sorry, Mobuck, I guess I should have phrased my question better. I understand everything you posted and I completely understand the reasons for each system. Your answer doesn't explain why blowback isn't operated by the recoil of the cartridge firing and pushing back against the bolt.
 
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As I understand it. Blowback is operated by the recoil. And that the weight of the slide and recoil spring is heavy enough to hold the gun in battery until the pressure is lower or the bullet has exited the barrel. Then the recoil of the case blows the slide back. I don't understand how gasses are going to get back past a case to drive the bolt open without some kind of gas system. Then again I'm no John Moses Browning. [emoji2]
 
I might as well weigh in also.

James K (post #15) has it exactly right. Locked breech, recoil operated systems work on the principle of a momentum balance between the bullet and powder gasses and the locked barrel and slide. (One of the reasons that you can change a .40 S&W to a .357 sig by just swapping barrels and not changing recoil springs is that both bullets typically produce the same momentum.)

On a blow back system, the cartridge acts as a tiny piston, which is pushed by the powder gasses. That piston actually does "work" in the thermodynamic sense and the energy use would be a function of the distance the piston traveled and the change in pressure over that distance. However, those changes would be so small that I'm not sure they could even be calculated and for sure not measured. (What snyper said in post #2.)
 
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