I had an acquaintance back in that era who traveled all sorts of back roads visiting itty-bitty factories in rural GA, AL, MS, and the FL panhandle as an industrial coatings rep.
He kept a MAC-10 in .45 ACP under his car seat with a couple of spare mags. Not joking. Those things were popular around here back then (ATL-area).
Yep. Mitch Werbell and that bunch made them in GA I believe. “Crude but effective.” The SMG that works equally well as a hammer. As they used to say, “Perfect for a shootout in a phone booth.”