US Patent 9494375 Universal AK-47 and variant bolt hold open follower

A universal cartridge follower for a firearm magazine comprising a cartridge receiving surface and side walls extending from the cartridge receiving surface. The cartridge receiving surface is operationally configured to intercept a firearm bolt. The side walls extend from the cartridge receiving surface and have opposing first surfaces defining a first width of the cartridge receiving surface and at least opposing second surfaces defining a second width of the cartridge receiving surface.