odd cartridge head stamp 5 91 (nothing esle )

[ivan salis]

any ideals? -- fairly large sized straight wall casing

 

[Monty]

A picture and some measurements would make all the difference in IDing the cartridge case. Being straight walled it is not likely a machine gun cartridge. My best guess would be a .45-70 government made in May, 1891. If so, it was probably manufactured by the Springfield armory? (that's a guess)! In fact with the limited information, this is all a guess! Monty