Please Educate Me With Regards to Typical Pressure Losses

i was thinking along the lines/in terms of optimal handgun design. . . .

similar to a single shot, over and under, or side by side rifle and shotgun.

Thanks!

- MN
:)
 
Revolvers lose some pressure due to the barrel/cylinder gap. I don't know where you'd find comparative data between a vented/unvented test barrel. You can go to the ballistics by the inch website and see some comparisons between the velocity of a single-shot pistol vs a revolver for some calibers, but what it works out to is that individual firearms show so much variability that it's hard to say what's due to the barrel/cylinder gap and what's due to the individuality of the firearm.

There is no pressure loss in recoil operated (locked breech) or blowback semi-autos. There is no venting before the bullet exits the barrel.

Gas operated semi-automatics do lose some pressure, but there aren't very many gas operated handguns. My comments above about revolvers would apply to the velocity lost in gas operated handguns. The individual variability from one firearm to another would likely be larger than the loss of pressure due to venting for gas operation.

The two guns you list are gas-delayed blowback which is different from typical gas operation. The guns you list use gas pressure to prevent the breech from opening too soon while a typical gas-operated handgun (like the Desert Eagle) vents gas to operate the action, not to hold it closed.
 
gas port fouling. . that makes sense. .

Desert Eagle- Thanks for the link. i hadn't heard of them yet. Pricey. .

Question, if you don't mind, about the recoil operated. .

Is the slide retracting without pressure loss as the bullet travels through the barrel, and if so, does the slide retraction assist in recoil reduction?

If so, is this possibly why the .40cal P226 i have shot may have possessed less recoil than my SP101 w/ .38spl + P?

Something about that delayed slide action that seems/seemed unnatural after shooting primarily wheelguns. . . .

Thanks,
:)

Ops, 10 o'click- time for a bowl of Old Gowerie. . . .
 
In a recoil operated handgun, the slide and barrel are locked together and travel rearward together due to the force of recoil until the unlocking mechanism allows them to separate. Unlocking should happen after the bullet has exited the bore so no pressure is vented until the bullet is already gone.

Recoil is due to conservation of momentum, and momentum can be calculated by multiplying mass by velocity. So the momentum of the ejecta (what exits the muzzle--bullet & combustion gases) must be equal to the momentum of the slide and barrel. The slide/barrel begin moving together as soon as the bullet starts moving, but since the mass of the slide/barrel together are much greater than the mass of the bullet, they move much more slowly than the bullet.

Felt recoil is a subjective thing. Sometimes grip fit/gun fit can make a big different in how the shooter perceives the recoil.
 
Gas operated semi-automatics do lose some pressure
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I'll have to disagree with this. At least, in the practical sense. There might be a tiny amount of pressure "lost" before the bullet clears the barrel, but it is insignificant, if it even exists. In the gas operated handguns I am familiar with, no gas is vented before the bullet is out of the bore. A small amount of gas is channeled from the barrel to operate the action, true, but the "dwell" of the system unlocking (due to the design) means the bullet has left the bore and pressure drops before the gun unlocks.

Pressure inside the barrel and gas system is constant, until after the bullet is gone. You can say that due to the extra volume of the gas system, total system pressure would be slightly lower than the same round fired from a non ported barrel, but in practical terms it is not significant.
 
The HK P7 loses a bit of pressure because of the gas system but it makes up for it with the hexagonal rifling which gives you about 5% higher velocity than standard velocity !!:rolleyes:

Either way it's what they call a moot point !
 
I have heard that if you take a bullet such as a 9mm and put it in a revolver with the same barrel that the revolver will loose about 10-20% of the energy.

The only place where an automatic could loose power over a revolver is in an automatic the chamber is counted as part of the barrel where in a revolver the chamber is not counted as part of the barrel so technically a 5 inch barrel is longer on a revolver. But from what I hear the cylinder gap is a bigger leach of your power then the "shorter" barrel.

Of course this is only internet rumors and I have not tested it my self so your mileage may very.
 
It would seem logical that the barrel to cylinder gap of a revolver allow the greatest amount of energy to escape of the three models presented.

One of the selling points of the Freedom Arms .454 Casull was the .003" barrel to cylinder gap which allowed less gas to escape that the more tradition .006" barrel to cylinder gap seem on S&W, Colts and other mass produced revolvers.
 
In the gas operated handguns I am familiar with, no gas is vented before the bullet is out of the bore.
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I suppose that's a reasonable view, although I hadn't really thought of it that way. I was thinking from the perspective that the gas diverted into the operating system and out of the bore was pressure lost in terms of the gas available to push the bullet.
I'll have to disagree with this. At least, in the practical sense.
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Agreed. Other than revolvers, there's not enough pressure loss to be a practical concern. Even in revolvers, it's not uncommon for the variations between individual guns to cause more velocity difference than the venting between the barrel & cylinder.
One of the selling points of the Freedom Arms .454 Casull was the .003" barrel to cylinder gap which allowed less gas to escape that the more tradition .006" barrel to cylinder gap seem on S&W, Colts and other mass produced revolvers.
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It's a tradeoff. Tighter cylinder gaps mean that the gun will tolerate less fouling before binding. For a pure self-defense or hunting firearm that's not an issue, but if you plan to take a revolver to the range for a prolonged session then 0.003" is probably too small unless you plan on doing at least some very basic cleanup every couple of boxes or so.

Obviously the .454 Casull isn't a gun that's likely to be shot all day so the very tight gap isn't a practical issue.
 
I compared velocities from my S&W model 17 revolver to the same ammo shot out of my S&W model 41 semi-auto pistol today. These two pistols have virtually identical barrel lengths, 7 1/4 inches for the semi auto and 7 1/2 inches for the revolver when measured the same way the semi-auto's barrel is measured, from the back of the chamber to the muzzle.

CCI standard velocity 40 grain target ammo.

967.98 fps semi auto
889.32 fps revolver

Federal Lightning high velocity ammo, 40 grain

1154.6 fps semi auto
1038.4 fps revolver

These were all averages of five shots.
Interestingly, my 24 inch barrel single shot rifle added only 69 fps to the velocity of the semi auto with CCI standard velocity ammo.
 
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