Question About Bullet Velocities In Revolvers.

V

Vilkata

New member
In a Bolt Action rifle, the bullet is sealed in, and the gasses can only escape out the end of the barrel. After ignition, the powder ignites, and the gasses expand, hurdling the bullet out of the casing, and down the barrel, and it continues to accelerate as long as the gas seeks to get out the barrel. So, a longer barrel generally means higher velocity.

Fairly obvious stuff.

But with revolvers, I often hear people say "yah, I got 1,025 FPS, out of just a 2 inch barrel!!". Because of the gap between the cylinder, and the barrel, huge ammounts of gasses are lost, so wouldnt the bullet use the barrel for greater accuracy, but not velocity? Or do the gasses just somehow shoot straight forward from the cylinder into the barrel? Somehow?

It seems like the velocity would be pretty much the same from either a 1 inch barrel, or a 6 inch barrel revolver.

Course, I know nothing.

That's why Im curious!

---Vilkata.
 
The longer barrels in revolvers do produce more velocity than the shorter barrels. The reason is that even though there is loss from the cylinder gap the cylinder gap can only allow a small amount of pressure to escape. The smaller the cylinder gap, the greater the restriction and the less pressure loss. The pressure wave will continue to push the bullet through the barrel even though there is pressure loss through the gap. Hence, you will have greater velocity out of a longer barrel unless your cylinder gap is like 1/2" in which there would be no restriction. (If you are into cars think of the gap as a wastegate on turbo cars that only allows a certain amount of exhaust gases to bypass the turbo)
 
Ahhh ok!

I figured it would have to be something like what you said. The pressure wave dissipating out the sides of the gap, but most of it continuing forward, into the barrel, and accelerating the bullet.

Pressure, gasses, bullets, and gaps pertaining to them are confusing... I just figured that gap would dissipate a lot more of the pressure wave I guess.

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A properly made revolver has a gap of ~.005" , with this gap the velocity loss is somewhere around 5% or less IIRC.
 
. . . and, in effect, the barrel is extended because it includes both the actual barrel length plus the portion of the cylinder's length from the projectile’s seat to the cylinder face. Thus, you lose slight pressure through gap, but you gain marginal velocity through pressure-force in the cylinder as well as in the barrel.
 
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