When it comes down to it, magazines are arguably the simplest mechanism in any firearm; a box with a spring and a follower that feeds bullets into the chamber. But as AR-15-pattern rifles became the standard for military, law enforcement, and civilian shooters alike, the world of AR-15 mags got a little more complicated. Today, not only are there numerous aftermarket magazines for the AR-15, but also a whole host of modifications and accessories for the mags themselves.