They added Werbell 's silencer to Ingram 's SMG and attempted to market it to the U.S. military for use in the Vietnam War .
In 1967 WerBell partnered with Gordon B. Ingram , inventor of the MAC - 10 submachine gun .
They added Werbell 's silencer to inventor 's SMG and attempted to market it to the U.S. military for use in the Vietnam War .
In 1967 WerBell partnered with Gordon B. Ingram , inventor of the MAC - 10 submachine gun .