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.
Benjamin Franklin nailed it when he said, "Fatigue is the best pillow." True story, Benny. There's nothing like pushing your body so far past exhaustion that you'd willingly, even longingly, take a nap on a concrete slab.