Staff Writer (Updated: 2/10/2016):
Design of the MAC-10 began as early as 1964 by Gordon B. Ingram. Ingram was a former associate at the Police Ordnance Corporation before leaving to develop the MAC-10. He partnered with Mitchell Werbell III, a former OSS and CIA operative and founder of SIONICS (Studies In the Operational Negation of Insurgents and Counter-Subversion) - a firm centering on the development and sales of firearm-capable suppressors and silencers and their partnership produced the Military Armament Corporation (MAC). Their joint venture and flagship product was to become the MAC-10 with the ultimate hope being quantitative sales to the US military during the ongoing Vietnam War.
To the casual observer, the MAC-10 showcased a design not unlike the Israeli-made UZI series (as well as other submachine guns that have mimicked this general design layout). The submachine gun was characterized by a rectangular receiver fitting a simple straight pistol grip that doubled as the magazine feed. There was a rounded-rectangle trigger ring ahead of the pistol grip and below the forward portion of the receiver. The safety catch was set to the right of the trigger guard. Construction was of steel stampings and the bolt was of a wrap-around - or telescoping - design, essentially "wrapping around" the barrel and allowing the MAC-10 to achieve such a short receiver length and thus remain a compact weapon system. These design elements made for a steady gun platform, concentrating the firing action balance just over the pistol grip. The cocking handle was situated along the stop of the receiver and accessible by either hand. Interestingly, there was a notch cut through the handle to ensure an unfettered line-of-sight between the operator, the weapon and his target. The cocking handle also doubled as a safety for it could be turned in a 90-degree action to lock the bolt and serve as a visual indicator that the weapon was made safe and unready to fire. The firing action was accomplished through an open bolt, blow-back operated design. A rather large ejection port opening was fitted along the right side of the receiver, corresponding to the placement of the magazine beneath it. A short sling could be attached to a hook at the front panel of the receiver.
The base MAC-10 model was chambered to fire the powerful man-stopping .45 ACP cartridge and could do so by way of a 30-round detachable box magazine. Muzzle velocity was rated at 919 feet per second with the heavy bullet and rate-of-fire was an impressive 1,145 rounds per minute. The removable wire stock was fully collapsible to allow for an ever more compact design. Overall length was 1 foot, 9.6 inches with the stock extended but the system could maintain an incredible length of just 10.7 inches with the stock completely removed. The length was increased to 2 feet, 7.4 inches with the addition of the sound suppressor (detailed below). Unloaded weight registered at 2.84 kilograms sans the suppressor.
It's All in the Barrel
Perhaps the most unique of all the MAC-10 features was its threaded barrel. The thread - similar to a bottle's top - was clearly visible just passed the forward portion of the receiver front and aft of the short protruding barrel. This was to support the Werbell-designed sound suppressor (a device different than a silencer). The sound suppressor could simply be screwed on over the threads for a tight fitting and allowed the operator to fire his weapon without the bullet velocity loss, a drawback inherent in a silencer. While not truly a "silenced" weapon, the firing action of a suppressed MAC-10 was akin to that of small "crack" sound, helping the operator still maintain some element of surprise or concealment from an alert enemy.
The suppressor used in the MAC-10 had a two-stage design clearly seen in available photography. The first stage offered a large cylinder that fed into a longer, slimmer cylinder. The resulting design proved a very quite sound suppressor when in practice and could efficiently double as a foregrip in adding additional close-quarters, two-handed stability to the submachine gun. Weighing in at just 1.20 pounds, the 11.44-inch suppressor system did not increase the weight of the MAC-10 by much, making the complete system quite manageable to handle, even if firing the weapon with one hand.
The MAC-11 existed as a near-identical version of the base MAC-10 save for its overall smaller dimensions and its chambering for the 9mm "Short" cartridge. The intent with this design was to market it for interested police and security forces already making use of the 9mm Parabellum cartridge but in need of the firepower inherent in a compact submachine gun body. The MAC-11 fired the smaller caliber cartridge through a 32-round detachable box magazine. Muzzle velocity was reported at 1,201 feet per second while rate-of-fire was roughly 1,090 rounds per minute.
Success Proves Elusive
Success for the MAC-10, as a series, proved quite elusive during her tenure. The submachine gun was showcased by a few, usually special, groups around the globe including the United States Navy SEALs during the Vietnam War from 1970 to 1976. Military Armament Corporation proved to be underfunded for the venture and soon went into bankruptcy. Additionally, recent restrictions were placed on the exporting of sound suppressors to foreign markets. Since the suppression capabilities of the MAC-10 were one of its major selling points, interest parties on the global stage soon backed away from potential purchases and some orders in process were cancelled outright once the export restrictions were announced. Military Armament Company went out of business in 1976. The MAC-10 design, however, lived on as it was passed from firm to firm, each attempting - in turn - to profit from the unique submachine gun. None were able to save the MAC-10 and production of the system concluded in 1986.
While an innovative weapon in its own right, and the unaccredited star of several Hollywood productions (including several television appearances), the real-life MAC-10 failed to have the commercial impact that was expected despite her popularity in premiere circles.