We dropped crates of Thompsons and Grease Guns to the French during the war. They used them until the ammo ran out. The only Allied weapon that was common with the Resistance was the Sten, because the Resistance could make them and they could fire German ammo.
Full auto ownership isn't practical for civilians anyway. It's way too expensive and attracts too much attention. I'm not advocating it. But in the event of SHTF those actively engaged without automatic weapons will die. This is the consistant lesson of Afghanistan, Bosnia, Chechnya and Somalia, et al. Anyone concerned about SHTF needs to plan for this. Like I said, it's just food for thought.
then you take their weapon....