AK-47 Drums Review Chinese 100 Romanian 75
Channel: Military Industrial Museum
Date: 2012-02-05

A drum magazine is a type of firearms magazine that is cylindrical in shape, similar to a drum. Instead of rounds being stored flat, as in a more common box magazine, rounds in a drum magazine are stored in a spiral around the center of the magazine, facing the direction of the barrel.
 
There are several primary designs for a drum magazine. The most common of which cylinder drum type that has a spider gear assembly that has an opening in each gear for 2-3 rounds of ammunition and can be loaded from the rear, used primarily in the AK-47.
-From Wikipedia