A couple of barrel questions

[goose]

Are there any formulas or rules of thumb for how much velocity is gained or lost per inch of barrel length? I'm mainly concerned with 22-30" lengths. Do different cartridges or calibers respond the same assuming hunting weight bullets and "normal" velocities.

My other question is does powder burning rate have anything to do with barrel life? I assume long bullets would cause more wear, is that right?

 

[LouBoyd]

Are there any formulas or rules of thumb for how much velocity is gained or lost per inch of barrel length? I'm mainly concerned with 22-30" lengths. Do different cartridges or calibers respond the same assuming hunting weight bullets and "normal" velocities.

My other question is does powder burning rate have anything to do with barrel life? I assume long bullets would cause more wear, is that right?

There are too many variables to have a simple rule of thumb for velocity vs barrel length. An interior ballistics program like Quickload will do a pretty good job of predicting velocity for a given barrel length, bore, case capacity, powder, bullet weight, and bullet material. It even accounts for bore friction, The simplest rule is that for a given bore diameter the larger the case capacity the longer the barrel needed to use the cartridge efficiently, but not everyone wants to use cartridges efficiently.

Bullet friction is generally negligible in determining barrel life. Barrel damage is caused primarily by the high temperate of the propellant gases removing metal in the throat o the gun. A heaver bullet may cause more time of exposure of the barrel to the high temperature gas, but it would do about the same if it was frictionless. You could get a lot of barrel wear by shooting bullets nearly as hard or harder than barrel steel, but who would do that?

If you think of barrels on a gun like tires on a car you can quit worrying about barrel life even with the most radical big cartridges.