US Patent 10480880 Ammunition magazine

A detachable box magazine for firearms includes a hollow magazine tube extending longitudinally along a median plane. The magazine tube defines a single-stack portion extending to an upper tube end with an upper tube opening. The magazine tube defines a double-stack portion positioned below the single-stack portion and extending to a bottom tube end with a bottom tube opening. For example, opposite lateral margins of the front sidewall can have a stepped shape between the upper tube end and the double-stack portion. The rear sidewall can have a linear taper between the upper tube end and the double-stack portion.