The factors you mentioned are far more relevant than people give them credit for, but barrel length is relevant to port and muzzle pressures. Examples where this is relevant include shorter AR's where there are some powders which fit the desired gas patterns better than conventional loads, or if you have a muzzle device which works best at a certain pressure range.For achieving top velocity you use a slower burning propellant for long barrels and faster for short. False - optimum propellant burnrate is determined by the case capacity, bullet weight and bore diameter NOT barrel length
what you mentioned, mite as in maybe be true. but there are some exception to the rule. example a .308 caliber rifle will obtain a higher muzzle velocity with a longer barrel. ie: 28 inch barrels will have a higher muzzle velocity than a rifle with a 22 inch barrel, giving that the same powder and bullet weight is fired in both weapons. super slow propellants will give higher velocity with longer barrels. a .308 rifle will obtain higher velocity then a .308 pistol. so case capacity, bullet weight and bore diameter all have a bearing on velocity, but then with out an optimum barrel length you will never get maximum velocity out of any round you fire.The factors you mentioned are far more relevant than people give them credit for, but barrel length is relevant to port and muzzle pressures. Examples where this is relevant include shorter AR's where there are some powders which fit the desired gas patterns better than conventional loads, or if you have a muzzle device which works best at a certain pressure range.
Everything comes together, but as you said, case cap, bullet weight, and bore diameter are the foundation.
Ratatat was discussing, at least in my interpretation of his post, the powder selection for a given cartridge, not stating that cartridges go the same speed with the same powder regardless of barrel length.what you mentioned, mite as in maybe be true. but there are some exception to the rule. example a .308 caliber rifle will obtain a higher muzzle velocity with a longer barrel. ie: 28 inch barrels will have a higher muzzle velocity than a rifle with a 22 inch barrel, giving that the same powder and bullet weight is fired in both weapons. super slow propellants will give higher velocity with longer barrels. a .308 rifle will obtain higher velocity then a .308 pistol. so case capacity, bullet weight and bore diameter all have a bearing on velocity, but then with out an optimum barrel length you will never get maximum velocity out of any round you fire.