Is it an AR-15 myth? Or a 5.56 NATO cartridge myth? Or is it NOT a myth at all? One thing is certain: it's been circulating for a long time. Brownells Gun Techs™ Steve and Caleb, our intrepid Smyth Busters, are here to tell us if the 5.56 / .233 bullet really TUMBLES after it leaves the barrel. That tumbling, goes the theory, is why the 5.56 bullet is so deadly: it's goin' sideways when it hits the target! Maybe something IS sideways here. Steve postulates this notion got started in the early days of the M16, when the standard rifling twist was a slow 1-12". The 55 grain bullet did tumble AFTER it hit the target, but it flew straight and true from the muzzle until then. In order for any bullet to be accurate, it CAN'T actually "tumble" on its way to the target. The heavier 62 and 77 grain bullets WILL yaw after they exit a 1-12" twist barrel, but they don't actually tumble end over end! And at ranges 300 yards or less, they will be moderately accurate, at least close enough for government work. If you want to shoot heavier 62 or 77 grain bullets in your AR-15, get a barrel with the modern, faster, 1-7" and 1-8" twist rates. So the myth that the 5.56 NATO bullet tumbles through the air is BUSTED.
Building a replica of an early AR-15 / M16? You can get a Brownells Retro Rifle® M16A1 "skinny"-profile barrel with 1-7" or 1-12" rifling.
