How Much Does Barrel Length Affect 5.56 Bullet Velocity?
This video tests how 5.56mm bullet velocity changes with barrel length, using PMC X-TAC 55-grain ammo. Velocities ranged from 2,183 ft/s from a 7.5-inch barrel to 3,052 ft/s from a 20-inch barrel. Shorter barrels like 12.5 inches offer a good balance for AR pistols, while longer barrels like 18-20 inches approach the manufacturer's rated velocity.













