US Patent 7942091 Shotgun drum magazine

A magazine for shotgun shells for use with a shotgun including an open frame housing having a generally flat front and a generally flat rear portion connected and separated by spacers. The flat front and flat rear portions each include an annular groove, the annular groove forming an annular path along which the shells travel. A rotatably mounted cog wheel for carrying the shells along the annular path and a coil spring for rotating the cog wheel such that shells can be manually loaded into the magazine against a force generated against the spring and automatically dispensed by the spring.