Original MAC M10 - another view

Original MAC M11
 

Data for MAC M10
Caliber .45ACP, 9x19mm Luger/Para (.380ACP a.k.a. 9x17mm Short for M-11)
Weight 2,84 kg (1.59 kg M-11)
Lenght 269 mm (548 mm with open stock) (248/460 mm for M11)
Rate of fire 1100 rounds per minute (1600 rpm for MAC-11 in .380)
Magazine capacity 30 , 32 rounds
Effective range 25 meters 

The M10 submachine gun was developed in 1970 or so by Gordon Ingram at his Military Armament Company (hence the name MAC), based at Powder Springs, Georgia, USA. 
Since then, many companies manufactured exact copies or slightly modified clones of both MAC M10 and M11 (smaller version of M10, in .380ACP a.k.a. 9x17mm Short). To name few: RPB Inc (USA), SWD Inc (USA), Cobray (USA), Jersey Arms (USA). Some modifications also were manufactured abroad the USA. 
MAC M10 or its wariants were adopted by some special forces units and police units in USA and in some other countries, for example, Thaiwan. 

M10 is a recoil-operated, select-fire submachine gun. M10 fires from open bolt. The bolt has firing pin milled in its body (or pinned to it), and the firing pin is located near the rear part of the bolt, that "sleeves" the rear part of the barrel (to decrease the lenght of the gun). The receiver is made from stamped steel and consist of two parts - upper and lower. receiver parts are connected by steel pin at the front of the weapon. Charging handle is located at the top of the receiver and doesn't move with the bolt when firing. The muzzle of the barrel is threaded to accept silencer. 

Both MAC10 and MAC11 are compact and reliable guns, capable of delivering a good amount of firepower due to high rate of fire (1100 rpm for MAC11 and a striking 1600 rpm for MAC11 in .380). But the light weight and high rate of fire resulted in marginal accuracy and relatively short effective range, thus make the MACs the good choice for building sweeps and inside-the-vehicle operations (Israeli commandos used the MAC-11s in their Aircraft Hijack Resque missions, thank to its to great firepower and low probability of over-penetration ad ricochetes).