Velocity Increase?

[robhic]

I've been loading a lot of .45 Colt ammo recently for my Taurus Judge (yeah, I know ... ). It has been possibly the easiest cartridge, yet, to load due to its large size. All my loads are really looking good but with that 3" long cylinder hole and just a 2" bullet being fired through the 3" barrel, would the extra 1"+ of cylinder add a bit of velocity?

I don't have or have access to a chrono but it just hit me that the extra length to accommodate the 410 shot shells that the trusty Judge can fire might add some FPS for the regular bullets. Any possibility of that? Thanks!

[Unclenick]

This is always a source of confusion: A revolver barrel is measured from the back end of the forcing cone, while pistol and rifle barrels are measured from the breech face that the cartridge head bears against. So, when you specify barrel length in QuickLOAD or other interior ballistics calculator that is based on the latter measurement, you have to add the chamber length to it to get an accurate measure of total bullet base travel in the bore. The base travel is the important factor because that's where force due to pressure is applied to the bullet and final kinetic energy in the bullet at the moment it reaches the muzzle is the average force at the base (less friction) times the distance over which that force is applied (bullet travel). Several percent more velocity (3% is a typical number) is picked up from muzzle blast acting on the bullet base over the first few several calibers of travel past the muzzle, but that's harder to allow for accurately and will be about the same regardless of the next set of factors I will bring up.

Now, as to a velocity increase: the definitive answer is, maybe. You do have extra bullet travel. However, because the .410 shell is wider than the throat of a standard .45 Colt, the bullet spends a good portion of that extra travel with a gap around it that bleeds gas and the keeps down the pressure. If you use a soft lead hollow base bullet that upsets to the .4630" diameter to seal the gases off, then you should, indeed, get a little more velocity from it. If not, due to the gas bypass, you may actually get less velocity due to not letting the powder reach normal peak pressure. That's why I say "maybe". I've got more than one chronograph, but no Judge, so that's about as much as I can offer.

[robhic]

Uncle Nick, you're no fun! But I appreciate your comprehensive answer. Since I can't really check my speeds, if you woulda said "yes" I'd have been happy and wouldn't have known one way or the other! I'll just go with "maybe" and think that maybe I'm gettin' a few FPS extra - just for fun!

Thanks a lot for the schooling and your time!

[T. O'Heir]

"...extra 1"+ of cylinder add a bit of velocity?..." No. Isn't rifled and isn't part of the barrel. Mind you, it's not the rifling that creates velocity. It's the gasses.

[Unclenick]

T. O'Hier,

You contradict yourself. If you don't believe smoothbores can produce velocity, you should look up muskets. They have gas pressure, too.