The Ingram MAC-11 (Military Armament Corporation Moel 11 Advancement 1 or M11A1) is a machine pistol designed by Gordon Ingram at the Military Armament Corporation (MAC) during the 1970s. The weapon is a sub-compact version of the Model 10 (MAC-10), and is chambered to fire a smaller .380 ACP round. This weapon is sometimes confused with the Sylvia & Wayne Daniels M-11/9 or the Vulcan M-11-9, both of which are chambered for 9 mm Para. The M11/9 was made after the M11A1 and is seen by many to be a copy with upgrades. Like the larger M-10, the M-11 has open sights with the rear pinhole sight welded to the receiver. These sights are for use with the folding stock, as using them without the stock is nearly useless because of the initial jump of the weapon due to its heavy, open-bolt design. The M-11A1 also has two safety features which are also found on the Model 10A1. The charging handle rotates to the 90 degrees to lock the bolt in the forward position thus preventing the weapon from being cocked. The second safety is a slider which is pushed forward to lock the trigger, which in turn pins the bolt to the rear (cocked) position. This prevents the weapon from discharging even when dropped, which is a typical problem with the open-bolt design.