US Pat. No. 10,508,874


9579087 Canada Inc., Nor...

1. An ammunition magazine for use with a firearm, said firearm comprising a lower receiver and a magazine catch for attaching the ammunition magazine to the lower receiver,said ammunition magazine comprising a container body for carrying ammunition cartridges, said container body having a bottom end defined by a bottom door, a side wall extending upwards from the bottom door an open top end which is attachable to the lower receiver by the magazine catch,
said ammunition magazine comprising a follower positioned inside the container body, and a follower spring positioned between the follower and the bottom door, wherein the follower spring provides force to bias the follower and the bottom door so that the follower moves up the side wall as ammunition cartridges are used,
wherein said follower further comprises an outwardly extending protrusion, said protrusion making contact with and moving the magazine catch when the last ammunition cartridge has been stripped from the ammunition magazine and the follower has moved up above the open top end of the ammunition magazine, such that the ammunition magazine is detachable from the lower receiver.