Patent ID: 8037800

Claim:
A detachable magazine for storing and delivering ammunition to a firearm having a magazine well, the magazine comprising: a body having a column adapted for insertion into the magazine well; the column defining a passage for transmitting ammunition to the firearm, the column configured to receive a double stack of cartridges; the body including a drum housing defining a pair of chambers communicating with the column passage; a first sprocket element rotatably received in each chamber and having a periphery adapted to receive a plurality of ammunition cartridges; a second sprocket element rotatably received in each chamber, and concentric with the first sprocket element, and having periphery adapted to receive a plurality of ammunition cartridges; a crank arm with a first end pivotally attached to the first sprocket element and a second end attached to a linked group of dummy rounds; a spring element operably connected to at least one of the sprocket elements in each chamber, and operable to rotatably bias the sprocket elements to transmit cartridges from the drum chambers to the column passage; and an ammunition guide element centered on the column, and operable to guide ammunition from one drum to one side of the column, and to guide ammunition from the other drum to another side of the column.