Due to short barrel, the vehicle-fifteen SMGs endured from a loud and bright muzzle blast, and quite a few muzzle devices were produced to reduce this. The SMGs ended up originally fitted Using the standard M16 rifle's "duckbill" or 3-prong flash hiders, which didn't alleviate the problem. In September 1966, Colt developed a 3.five-inch (89 mm) pr