> it was fun watching my 10 inch 556 crack the ceramic and catch in the kevlar while his 16 inch blew through it like it wasnt there. i learned that day why gun fags argue over inches. it can and does make a difference   > never get a barrel shorter than absolutely necessary; (to a point) the longer the barrel the higher the muzzle velocity check't the explosion that happens inside the case, to push the round down the barrel, has not fully finished its burn until 2/3rds the way down the barrel. if you use a short barrel you can push the projectile out of the barrel before the remaining powder is burnt. this makes a big fireball out of the muzzle but its wasting energy. a longer barrel will capture this burn of powder and continue to help increase the velocity of the projectile as the powder burns and pushes the projectile further and further down the barrel. if you watch any hard core durability tests on an ar with multiple drums you can always see the barrel start to glow about 2/3rds the way down the barrel. the powder is producing a flame front that far down the barrel and it helps produce more velocity to the projectile when you have a barrel longer than wherever this flame front is. its normally about 12-15" down the barrel depending on the round. this is why the shortest you want is a 14" barrel but you typically need a 16" barrel to get the best results. if you use a short 8-10" barrel you are blowing the flame front out the end of the barrel before its helped push the projectile to its maximum velocity. using a 10" barrel 300blk with subsonic ammo, the velocity is so slow the projectile literally wont get enough twist or velocity to keep itself on target. at 120-140 yards the projectile will begin to tumble and you can see the round go thru paper targets sideways as it tumbles. and have serious difficulty grouping in 6" at 120 yards. you swap to a 16-18" barrel and you can group at 200 yards with the same gun and ammo.
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