I got one. big,heavy,waste of time.
For a fighting rifle you might have to carry or maneuver with (rather than a long-barrel full-auto weapon fired from an emplacement), a better, cheaper, set-up than a drum for large AK ammo capacity for defending a position (like your home) from thugs, rioters, zombies, etc. is to
get your hands on a couple of 40-round Bulgarian steel surplus magazines, originally designed for the RPK machine gun. Take two 40-rounders and
use a quality magazine coupler (like the one from Fobus) to mount the spare mag on the left side of the primary mag in an inverted orientation (floorplate of the spare is adjacent to the top of the primary), with a slight vertical offset to allow room for the "rock and lock" motion during the change. I put a rubber magazine cap on the end of the spare mag to keep crud out of it during storage.
This set-up gives you higher capacity, lighter weight, and better handling than a drum, and requires only one change that can be completed much faster than a standard mag change with retention. An experienced operator recently introduced me to this trick, and he said in a pinch duct tape will work as well as anything else. Just prior to the ban I bought a couple of unissued 40-round mags and couplers to join them pairs for less than fifty bucks...
