f you’ve spent much time on Instagram lately, you may have seen in certain circles a trend away from barreled ARs to the original long boys. short-With velocities being what they are and that long-standing thing called physics, longer barrels are appealing, particularly in a caliber such as 5.56x45mm. With 55-grain being the most common projectile for the platform, muzzle velocity from an 18-inch barrel could hover around 3,000-plus fps while a 10-inch(ish) barrel could be closer to 2,400
