Barrel Length and pressure

[longbow62]

Not sure what part of forum this belongs in. I don't consider myself a newb compared to the average shooter, but you guys are not your average shooters/reloaders.

In cases of over pressure does barrel length play a role? I have read the longer the barrel the lower the pressure of an identical charge in guns with all else being equal but barrel length. Muzzle blast is obviously more pronounced and to my shoulder the recoil is sharper in short barreled guns. Does this mean pressure is higher?

I have read can you think about a water hose. The longer one has lower pressure. Does a hot load in a short barreled gun become less hot in a gun with a longer barrel? I hope I have made my question clear.

 

[Grump]

Re: Barrel Length and pressure

Barrel length affects only pressure at the muzzle.

Higher pressure at the muzzle does equal more "thrust" from the exiting gases--doubling the velocity quadruples the energy.

I'm not sure that the shorter barrel time (quicker transition to gas thrust) would have a discernible effect.

Recoil is a function of the velocity of the TOTAL mass accelerated down and out the barrel. That's why my 125-gr .357 Mag loads with a 125-gr bullet at 1300 fps from a 21-gr powder charge kicked almost exactly the same as the 140-gr loads using a charge of 10 grains or so, at the same velocity. It's bullet weight plus powder charge.

The peak chamber pressure hits with bullet travel of about 2 inches in standard-ish rifle calibers. From there on, it's all downhill.