Colt SMG: First of the 9mm ARs

With the expansion of SWAT teams throughout law enforcement in the 1980s, Colt realized that it was leaving a lot of sales on the table by not having a submachine gun it could offer alongside M16/CAR-15 rifles and carbines. They addressed this in the early 1980s by adapting a CAR-15 to 9x19mm. It used an adapter in the magazine well to fit modified Uzi pattern magazines (they were given hold-open tabs on the followers), and retained the same handling and controls as the full size AR. The SMG was made as a closed bolt, hammer fired, simple blowback action. By adding weight to the bolt carrier and buffer, the rate of fire was kept down to around 800 rpm.

The Colt SMG never really captured wide appeal. It was reasonably successful for Colt in large part because of their ability to market it alongside rifles, but it was dogged by reliability problems. A bunch of different models were made with different fire control options, including a couple civilian semiautomatic models and the distinctive DoE “briefcase gun” and the integrally suppressed DEA model, although neither of those saw very substantial sales. Still, it remains available to this day.

Colt 633 DoE Reproduction: https://forgottenweapons.vhx.tv/videos/psa-doe-9mm-4k