The Winchester Model 1912 (also commonly known as the M12, or Model 12) is a pump action, hammerless slide-action, shotgun with an external tube magazine.
Often referred to as the Perfect Repeater since its introduction, it has largely set the basic standard for pump action shotguns over its 51 year high-rate durable production life. Nearly two million Model 12 shotguns were produced and manufactured, from 1912 until first discontinued by Winchester in 1963. The M12 was produced in various barrel lengths and grades. Only the 12 and 16 gauge versions came out in 1914 though it was initially chambered for 20 gauge, only. The M12, 28 gauge version came out in 1934.