The Military Armament Corporation gun mac 10, officially abbreviated as “M10” or “M-10“, and more commonly known as the MAC-10, is a compact, blowback operated machine pistol/submachine gun 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 abates the noise created, but makes it easier to control on full automatic (although it also makes the gun far less compact and concealable)
The mac 10 gun is built predominantly from steel stampings. A notched cocking handle protrudes from the top of the receiver, and turning the handle 90°, locks the bolt, and acts as an indicator the weapon is unable to fire. The MAC-10 has a telescoping bolt, which wraps around the rear face of the barrel. This allows a more compact weapon and balances the weight of the weapon over the pistol grip, where the magazine is located. The MAC-10 fires from an open bolt, and the light weight of the bolt results in a rapid rate of fire.
In addition, this design incorporates a built in feed ramp as part of the trigger guard (a new concept at the time) and, to save on cost, the magazine was recycled from the M3 Grease Gun. The barrel is threaded to accept a suppressor, which works by reducing the discharge’s sound without attempting to reduce the speed of the bullet. This works well with the .45 ACP versions, as most loads are subsonic already, as opposed to special, low-powered subsonic loads usually required for suppressed 9mm weapons.
At the suggestion of the United States Army, the suppressor also acts as a foregrip to inhibit muzzle rise when fired. Ingram added a small bracket with a small strap beneath the muzzle to aid in controlling recoil during fully automatic fire. The original rate of fire for the MAC-10 in .45 ACP is approximately 1090 rounds per minute. That of the 9mm is approximately 1250, and that of the smaller MAC-11 in .380 ACP is 1500 rounds per minute.
Noting the weapon’s poor precision, in the 1970s, International Association of Police Chiefs weapons researcher David Steele described the MAC series as “fit only for combat in a phone booth”.