Federal XM 5.56mm NATO Steel Core Full Metal Jacket Boat Tail Rifle Ammunition. This is the famous and hard to find mil-spec M855 steel core 5.56x45 (in green tip in) penetrator ammo you have heard about. Each round is brass-cased, boxer-primed, non-corrosive, and reloadable. It is both economical and precision manufactured in the United States. 20 rounds per box.
NOTICE: While the 5.56x45mm NATO will fit in a .223 Remington chamber, the 5.56 is a military round that runs at higher pressures than its .223 counterpart and is not recommended to be fired in a .223 Remington chamber.