Ingram/MAC-11
.380 ACP or 9x19mm
This is based on the original MAC-10 designed in 1964 by Gordon Ingram, known as the Military Armament Corporation Model 10 (MAC-10), which was significant for its effective two-stage suppressor. This is the later 1972 MAC-11 with an even more effective suppressor. However it has a high rate of fire and will empty a 32-round magazine of 9mm in just around 2 seconds.
It's considered extremely inaccurate and has only been used by a handful of militaries around the world in small numbers, including US Navy SEALs in Vietnam and Israeli Mossad (MAC-10) and the Venezuelan paramilitary Criminal Investigation Corp.