The Military Armament Corporation Model 10, officially abbreviated as "M10" or "M-10", and more commonly known as the MAC-10, is a compact, blowback operated machine pistol that was developed by Gordon B. Ingram in 1964. It is chambered in either . 45 ACP or 9mm. A two-stage suppressor by Sionics was designed for the MAC-10, which not only abated the noise created, but made it easier to control on full automatic (although it also made the gun far less compact and concealable). For a decade, the semi-automatic pistol version of the weapon was forbidden in the U. S. under the assault weapons ban enacted by Congress in 1994.