Do revolvers lose velocity as compared with semiautos?

Wow. I'm constantly impressed at the information that comes out of these threads and the fact that the discussions remain so civil even when there are disagreements about some issues.

CraZivn-you are correct that the energy to operate the slide must come 'from somewhere' but it doesn't mean the bullet velocity has to be lower. Let me take a crack at explaining it this way (and I'll take 'corrections' from more knowledgeable folk gracefully)

-the energy to run the slide is 'waste' energy or 'leftover' energy after the bullet leaves the gun and you might possibly notice it in less felt recoil from a semi-auto than from a revolver. That is, the some of the recoil might be used by the semi-auto mechanism and the 'felt' recoil of a semi may seem lower than that of a revolver or a single shot.
 
James K said:
The energy to function a recoil-operated pistol comes from (duh!) recoil, and that begins when the bullet begins to move. By the time the bullet exits, the slide has already picked up enough inertia to continue the cycle.
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Absolutely correct. If we think about it, it becomes obvious that the instant that the bullet leaves the barrel there's nothing pushing on slide any more--that means that the slide is only being pushed while the bullet is in the barrel. It also means that when the bullet leaves the muzzle, the slide is moving as fast as it ever will. It only slows down from friction and spring resistance from that point on.
Conversely, it could be argued that semi-autos lose velocity because a portion of the round's energy is absorbed in pushing the slide back to cycle the action.
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The slide is pushed back by recoil, and the revolver is also pushed back by recoil. To the extent that either one of them loses any energy to recoil, they both lose energy to recoil. The only difference is that some of the recoil in a recoil-operated semi-auto is put to good use while in a revolver all it does is move the gun around. Basically pretty much what DaleA said.
I believe I've always read and heard that revolver barrels typically measured from the face of the cylinder to the muzzle, not from the forcing cone forward. Not enough difference to matter, but I did see a study of variation in the actual length of four-inch revolver barrels, and that's how they measured it.
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You could very well be correct--I can't recall ever seeing anything that clearly specified one way or the other which could be because I just wasn't paying attention. If that's right, it's interesting to think about measuring empty air (the cylinder gap) as if it's part of the barrel length, isn't it? :D
The ideal gap is .006"-.007"; the .001" mentioned above is entirely too small and will give trouble.
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Good point. I should have clarified that the BBTI website was using that barrel/cylinder gap in the test as an experiment only and there was no intent to imply that a gun should be actually set up that way for general use.
 
Bob Wright -
I have loaded .45 ACP ammo with a 185 gr. JHP bullet that clocked 1290 fps. out of my 5" S&W Model 625
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when an expert tells me not to use 'em in an autoloader I would do as you have and believe them.

That said, Buffalo Bore sells 220 grain 10mm rounds they say comes out of a Colt Delta Elite at 1175 fps.

https://www.buffalobore.com/index.php?l=product_detail&p=219

Personally I've always thought these load would batter a 1911 something fierce but I'd like to get a Glock someday in 10mm because I don't like Glocks as much as 1911's :D. I realize if I did get a Glock I shouldn't use the BB hard cast, I'd use jacketed bullets.
 
when an expert tells me not to use 'em in an autoloader I would do as you have and believe them.

That said, Buffalo Bore sells 220 grain 10mm rounds they say comes out of a Colt Delta Elite at 1175 fps.
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The difference is that the Delta elite, while still being a 1911 variant, is specifically designed for the much higher pressure of the 10mm. It has different springs, and IIRC the frame is different. The standard 1911 is made for much lower pressure 45 acp rounds. Apples and oranges.
 
If you want to really confuse the issue - add in a 3rd type of pistol. Even an autoloader looses a tiny bit of velocity due to some escaping gasses as the slide opens. Shoot that same bullet out of a closed breech firearm like a Contender/Encore and you'll see more of that gas converted into projectile velocity. True, the gain might be small but it will still be measurable.
 
Most folks have a problem with understanding recoil. It is not gas pressure pushing back on the slide, since the gas pressure is the same in all directions at any given instant. Newton says that for every action, there is an equal and opposite reaction - the bullet moves forward, the gun moves back. That's it. Gas cannot escape in any significant amounts* since in a recoil operated pistol the barrel and slide are locked together until an outside force (the cam or the link) unlocks them. Until that time, they are just as tightly locked as the bolt of a Mauser rifle. If you take the slide and barrel off a 1911 pistol, load a round in the chamber, lock the parts together and fire the round (electrically), the whole assembly will recoil, but the barrel and slide will remain locked together.

As for the slide moving back in relation to the frame before bullet exit, that is exactly what it should do. The slide-barrel assembly begins to recoil the instant the bullet starts to move, so it is moving back as the bullet moves forward in the barrel.

*Some gas escapes around the bullet, especially with jacketed bullets which do not fully conform to the rifling grooves, and around the cartridge case before full obturation takes place, but those circumstances can happen in a revolver also.

Jim
 
Shoot that same bullet out of a closed breech firearm like a Contender/Encore and you'll see more of that gas converted into projectile velocity. True, the gain might be small but it will still be measurable.
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I would be willing to be that if fired from the same gun, say a 1911 where the slide was not allowed to move versus one that was (JamesK's electronically fired example), the difference in velocity would be so insignificant as to fall within the normal range of variation for a given loading.

As noted, the rearward push is going to occur whether the slide moves or not. If the slide does not move, that energy is just going to be transferred into the shooter...who will move accordingly relevant to the applicable conditions that apply.

It would be an interest test to see how things work out. Mount a gun to a fixed platform by the frame such that the frame will not physical change locations under recoil. Only the slide will move when fired. Fire 15 shots from a given lot of ammo. Repeat the test with pinning or otherwise holding the slide in position. Unmount the gun and then fire by hand. Compare results.
 
Thanks Winchester_73 for the information on the Colt Delta Elite. That is useful information to have and I did not know it.
 
The velocity loss at the barrel/cylinder gap of a revolver is more than made up for by the revolver being able to fire a more powerful cartridge than an auto pistol without becoming an unwieldy weapon. A 125gr 357 Magnum fired from a two inch barrel has a higher velocity than any 9mm fired from a service size pistol, and will only pick up speed as barrel length increases. The 10mm is as powerful a round as is loaded in a conventional auto pistol with ammo that is readily available but the 41 and 44 Magnums outclass it in velocity and bullet weight in reasonably sized revolvers. My 5.5 inch 45 Colt Blackhawk with standard loads is more powerful than my 4.75" 45 Auto Witness Elite Match. With Ruger-only loads in the 45 Colt there is no comparison. Pistols and revolvers both have their pluses and minuses but the barrel/cylinder gap velocity loss is not among them.
 
I have a 5" 1911 and a 4" revolver both in .45 ACP. The 1911 vel. is about 50fps faster than the 1911 with my regular load. This isn't enough difference that I worry about it. Revolvers in general are more versatile than autos. You can load lighter loads, heavier or lighter bullets, they are available in much more powerful cartridges and they are more reliable than autos. It just depends on what you want. I really like the .45 ACP in the revolver or the 1911. If I hunted with a handgun it would be a .44 Mag revolver.
 
Great information. My appreciation for revolvers has gone up a lot. Thanks to everyone for the excellent explanations.
 
A 125gr 357 Magnum fired from a two inch barrel has a higher velocity than any 9mm fired from a service size pistol,
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Not true. Part of the reason folks observe that revolvers lose more velocity is because of unrealistic published data. The loss from a cylinder gap is there, but only a small part of the velocity loss.

If you look at almost all published data they show 357 and 44 magnum velcocities from 7.5"-8" test barrels. When shot from 2", 3", 4" or even 6" barrels that is the equivalent of shooting a 300 magnum from a 6", 9", 12", or 18" barrel. No one would expect a 300 mag to come close to advertised velocities from a 6" or 9" barrel, but seem surprised when a 2" 357 magnum comes up short.

Semi-auto published ballistics are from much more realistic 4"-5" test barrels, and are usually much closer to what you actually get. My 4" G-19 is lighter and shorter than any 2" 357 mag and gets 1250 fps with 124 gr 9mm+p ammo. Most 4" revolvers will only beat that by about 50-100 fps. A 2" gun won't be close. Only 900-1050 fps according to these guys.

http://www.ballisticsbytheinch.com/357mag.html
 
Gas cannot escape in any significant amounts* since in a recoil operated pistol the barrel and slide are locked together until an outside force (the cam or the link) unlocks them.
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Exactly because it is a closed breach (sealed on one end) until the slide moves back enough to extract the shell as the slide starts back from the recoil. By the time the slide moves back to expel any trapped gases the bullet is long gone. (deja vu)

Plus the effect of the expanding gases that create the velocity stop making an impact on the bullet velocity after the bullet passes a few inches from the muzzle.
 
JMR40

Beg your pardon, My 1-7/8" 642 gets 900fps with a 125 jhp, A .357 at twice the pressure is gonna outrun any 9mm with 124 gr. 9mm 115 only run 1000 out of my LC9. This verified by 2 different chronographs, not just the book.
 
My 4" G-19 is lighter and shorter than any 2" 357 mag and gets 1250 fps with 124 gr 9mm+p ammo. Most 4" revolvers will only beat that by about 50-100 fps. A 2" gun won't be close. Only 900-1050 fps according to these guys.
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I don't know about 900-1050 fps, I haven't seen that. What I have seen is my 2.25" SP101 launch Federal 125gr JHPs at an average velocity of 1232 fps over my Pact Professional set 15 feet from the muzzle. My 4" GP100 launches them at over 1400 fps. I doubt the extra quarter inch of barrel on the SP101 is boosting velocity by ~200 fps compared to a two inch 357. I've chronographed 9mm through my 6.5" Blackhawk convertible and standard pressure Federal 124gr loads come out around 1125 fps. What brand of chronograph did you use to clock the 9mm +P from your Glock? What brand of ammo was it?
 
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It's like truckers used to talk about CB radios. Who cares? Unless you are an engineer making ammo or guns velocity losses and gains from revolver to autos in minimal. Just remember this. For the piddly amount of energy loss in a wheel gun, you make up for it in accuracy.
 
I shot .45 ACP rounds through a 2.5" revolver, and a 4.25" auto, and the rounds went faster through the former. That's significant really only for comparing those two guns, but there you go. The effective barrel length of the 4.25" auto is more like 3.35", as the chamber is included in the auto's barrel length, but we're still talking a 3/4" difference in "bore length", and the shorter one, with the cylinder gap, was faster.
My own 4" revolver will not attain the same velocities as my 5" auto, even though the "bore length" is almost identical for both.
There's clearly a difference between the theory and physics, and what you see on the range.
 
ive seen online and maybe in print someting concerning semi auto cartridges in a revolver. article was by a guy who found out that the cylinder in the blackhawk convertable was giving his semi auto cartridge 50-100 fps more velocity then the same load in a semi auto with the same listed barrel length.
 
Not enough to notice the difference and most auto-loaders can't handle the larger Pistol caliber rounds anyway. So, it is an apples-oranges comparison that really isn't valid. (How many .44Mag auto loaders have you bought?)
 
ive seen online and maybe in print someting concerning semi auto cartridges in a revolver. article was by a guy who found out that the cylinder in the blackhawk convertable was giving his semi auto cartridge 50-100 fps more velocity then the same load in a semi auto with the same listed barrel length.
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As noted, comparison of two specific guns, or several doesn't really matter in the grand scheme. Subtle differences in design or manufacture, or use wear, may make one model produce higher velocity than the exact same model using the same batch of ammo. So 2 Blackhawks shooting the same ammo may have different velocities. Two Colt 1911s shooting the same ammo may have different velocities.
 
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