A shotgun shell magazine to be received within a mil-spec magazine of an M16/AR-15 mil-spec firearm is disclosed. The magazine has an open top end defining a cavity configured to receive one or more shotgun shells. The magazine body includes a feed lip which partially occludes the open top end and a rim edge including a vertical edge strip which defines a gap in communication with the cavity. A follower having a ramped upper surface resides within the cavity. The follower is biased to direct the shotgun shells toward the open top end until the primer end of a top most shotgun shell engages the feed lip. The top most shotgun shell is angled with respect to the open top end and at least a portion of the closed end of the top most shotgun shell lies above a plane created by the open top end.