Thread: Myth? - shorter barrel = use faster powder?

if you take it to extreme ...or go backwards in time...or both... black powder achieved better burns with long barrels..... folks used to TUNE a load by shooting over snow,and keep reducing powder charge till no unburnt powder exited muzzle..... sort of the same as muzzle blast thing... my old 20" 270 had one heck of a muzzle blast and big ball of flame on dark with factory loads...feed it heavy projectiles,not so bad.
a faster powder that has completed its burning inside barrel wont waste energy on muzzle blast/fireball.....
slower powder needs longer barrel to complete its burning...same as black powder.... if you dont burn it all in the length of barrel you have,you may as well reduce the charge until you do,BECAUSE you wont make projectile go any faster with more powder....I BELIEVE this is the flat spot folks look for on ladder testing???
or very similar....
shotshells use a very fast burning powder and short barrels still produce horrendous fireballs,maybe the lower pressure plays part??? ...long barrels are much nicer to use and as bonus take the bang further away from your ears.