does a bullet loose velocity through a pistol over a revolver?
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Pond James Pond
New member
My guess, and it is a guess, is that it would be much of a muchness!
Yes, the pistol slide absorbs some energy, but the revolver looses some gaseous energy through the space between barrel entrance and cylinder exit.
If I had to guess further, I might say the revolver lost a bit less energy.
Yes, the pistol slide absorbs some energy, but the revolver looses some gaseous energy through the space between barrel entrance and cylinder exit.
If I had to guess further, I might say the revolver lost a bit less energy.
black mamba
New member
I, too, believe the barrel/cylinder gap of the revolver loses a little more velocity.
They got the 357 Sig up to 357 magnum velocities in the 125 grain offerings, so its close there.
Could match in larger grain bullets if they used a large frame semi auto for the base gun, but they like to keep it as small as they can so go with 9mm frames and not a 45 or a 10mm.
Be interesting if someone offers one up that in a larger frame someday (that I know of, could be wrong)
Could match in larger grain bullets if they used a large frame semi auto for the base gun, but they like to keep it as small as they can so go with 9mm frames and not a 45 or a 10mm.
Be interesting if someone offers one up that in a larger frame someday (that I know of, could be wrong)
The short answer is, it depends.
It depends, because of two things:
1) Cylinder gap. As black mamba and Pond already mentioned, the propellant gases have a chance to escape through this opening, depriving the bullet of a certain amount of pressure. The guys over at ballisticsbytheinch have recently posted test data about this phenomenon.
2) Different barrel lengths. You see, a semi-automatic barrel is measured from the back of the chamber to the muzzle. A revolver barrel is measured from the back of the barrel to the front, excluding the cylinder. This means that a revolver that is reported to sport a 4" barrel will actually have more real rifled barrel in which to accelerate the bullet than a semi that is reported to have a 4" barrel.
The only way to know which is going to give you more velocity is to test them both, although I believe that most semis with truly equal barrels (say a 4" revolver and a 5" semi) and a locking action will give just a smidgen more velocity thanks to the cylinder gap.
It depends, because of two things:
1) Cylinder gap. As black mamba and Pond already mentioned, the propellant gases have a chance to escape through this opening, depriving the bullet of a certain amount of pressure. The guys over at ballisticsbytheinch have recently posted test data about this phenomenon.
2) Different barrel lengths. You see, a semi-automatic barrel is measured from the back of the chamber to the muzzle. A revolver barrel is measured from the back of the barrel to the front, excluding the cylinder. This means that a revolver that is reported to sport a 4" barrel will actually have more real rifled barrel in which to accelerate the bullet than a semi that is reported to have a 4" barrel.
The only way to know which is going to give you more velocity is to test them both, although I believe that most semis with truly equal barrels (say a 4" revolver and a 5" semi) and a locking action will give just a smidgen more velocity thanks to the cylinder gap.
carguychris
New member
Felt recoil is difficult to quantify because it's subjective by definition.
That said, revolvers typically have more felt recoil than automatics of similar power and weight because they don't use a portion of the recoil impulse to cycle the action. ALL of the recoil impulse is transmitted to the revolver's frame.
The bullet is long gone from the barrel in a semi-auto, before the breech unlocks. The brass has sealed the chamber, and probably hasn't completely contracted yet.
The .003" plus gap is allowing powder to vent as the bullet is still in the barrel.
Given no further vaiables, seems like the higher velocity goes to the semi.
The .003" plus gap is allowing powder to vent as the bullet is still in the barrel.
Given no further vaiables, seems like the higher velocity goes to the semi.
Therealkoop
New member
Repeating pendennis here, a semi wont unlock until the bullet leaves the barrel.
High velocity to the semi.
High velocity to the semi.
Comparing velocities between different barrels gives no relevant info. Each individual barrel will be different. A "fast" 4" barrel on a revolver can very possibly yield more velocity than a "slow" 4" semiauto barrel. Two other specimens of the same models listed might give totally opposite results.
Crankgrinder
New member
I am aware that in Russia i believe they built a revolver that closed this cylinder gap with its action. The cylinder moved to the rear, rotated, then locked itself to the forcing cone when the hammer was pulled. The velocity gains with this pistol were like 30fps more than with a regular revolver. The design was scrapped because the gain was not worth the investment.
keep in mind that the cartridge being fired is not what activates a semiautomatic. That entire pistol is propelled backwards by recoil. the hand that holds the pistol prevents the pistol from completing the full recoil action. the slide, being unhindered other than by the return spring and hammer spring, goes into full recoil. the bullet has left the barrel before this has been significantly started.
There is no energy being diverted from the actual propulsion of the bullet to operate that slide, it is using wasted energy from the recoil of the firearm.
This is not relevant to gas operated systems, or to blowback systems, this is only applicable to locked breech recoil operated systems that are most commonly used on handguns.
both blowback and gas operated autloaders; in a blowback system, the bolt is being blown backwards the very second of ignition, and a lot of energy is diverted to that. In a gas op system, gas is actually bled off before the bullet leaves the bore, and of course, this will cause a slight loss of pressure and propellant gasses. This is going to be pretty insignificant, IMO.
I'd love to chrono my 742, garand, and my other 30-06 rifles and get mv figures. it should be interesting, after measuring from bullet tip to crown.
There is no energy being diverted from the actual propulsion of the bullet to operate that slide, it is using wasted energy from the recoil of the firearm.
This is not relevant to gas operated systems, or to blowback systems, this is only applicable to locked breech recoil operated systems that are most commonly used on handguns.
both blowback and gas operated autloaders; in a blowback system, the bolt is being blown backwards the very second of ignition, and a lot of energy is diverted to that. In a gas op system, gas is actually bled off before the bullet leaves the bore, and of course, this will cause a slight loss of pressure and propellant gasses. This is going to be pretty insignificant, IMO.
I'd love to chrono my 742, garand, and my other 30-06 rifles and get mv figures. it should be interesting, after measuring from bullet tip to crown.
Thank you for that description, Brian, I had never considered the operation of a handgun in that way. When you say that blowback actions allow greater energy to be lost than locking actions, do you know how significant this is? I'm sure some design engineer has equations for it, but I'm just curious if there would be a measurable difference in velocities from 380 autos with equal barrels but different actions.
The revolver you are referring to is the 1895 Nagant. The cylinder does indeed butt up against the forcing cone when locked up for firing. ALSO, the ammunition was rather unusual, having a very long case, and the bullet completely seated inside it, not just flush like a wadcutter. The empty "neck" of the case sealed against the bore when the cylinder meets the barrel, providing the gas seal.
Also, the revolver was in full service use through the Second World War, although not primary issue. Its retired now, and many have been sold in the US in recent years. The Russians (and the Soviets) rarely "scrapped" anything.
This is not technically correct. While there is rearward force exerted against the breechblock (slide) of a blowback action from the moment of cartridge ignition, it does not move until after the bullet has left the barrel, and pressure drops enough to allow the case to extract. The blowback system relies on inertia. The mass of the bolt (slide) and the tension of the spring are what holds the blowback shut until pressure has dropped to a safe level. The bullet is already long gone by the time the action opens. None of the energy propelling the bullet is "wasted" or diverted to operate the action.
In a gas operated system, yes, a little bit of gas pressure is tapped off the bore into the gas system, reducing by a tiny amount the gas pressure behind the bullet at the muzzle, compared to a barrel without a gas system. But the difference is insignificant. It is less than the variation of velocity one finds between different barrels, ported, or not. And, due to the design of gas systems, the action does not unlock until after the bullet has left the barrel.
There is a slight loss of pressure in a revolver, due to the cylinder gap, however, the actual velocity loss is relatively insignificant, and can vary greatly between individual guns.
Some guns are "faster" than others. Some are "slower". Quoted velocity figures for any given ammo are valid ONLY in the test barrel they are measured.
I have personally seen variances as great as 100fps (although half that, or less is more common) between different guns of "identical" caliber and barrel length.
Don't get hung up on a handful of fps, particularly in pistols. A 30, 40, or 50fps difference is literally, nothing of concern, and has no significant effect on performance.
man, that's right. I don't know what the heck was in my head. The breech block does not actually start to move until pressures have dropped.
If the breech block did start to slip, the loss of velocity would still be pretty insignificant unless you were dealing with a very short barrel on a handgun.
I gave my Dad one of those Nagant revolvers for Christmas a few years ago. The cylinder really did move forward and close the gap, it was remarkable. Of course, this feature gave it the most horrific trigger pull ever inflicted on a fighting revolver, and it is a bear to shoot accurately. The ammo is truly bizarre, but I suppose it might work as it's supposed to. Based on the measurements taken by the boys over at ballisticsbytheinch for their new site update, the gains aren't worth the liability of the trigger pull alone, let alone the additional complexity.