One of the issues I have seen brought before on the FA debate is that prior to the 1934 NFA there seemed to be no problem with FA/Military arms being owned by private citizens.
However, that begs the question of whether many if any civilians owned FA for reasons other than curiosity/hobbying reasons. I have no figures for this but I reason that the main if not sole users of FA weapons outside the police of military were criminals and that is why the NFA passed without much resistance. I don't think many civilians owned them due to 1) cost 2) unsuitability for hunting or sport 3) wasted ammo.
I know Thompson tried to market them to civilian farmers but it failed. Seems clear that these weapons were designed for military application and not civilian self-defense. Plus they had really only been available at all for about twenty or thirty years.
"God and the Soldier we adore, in time of trouble but not before. When the danger's past and the wrong been righted, God is forgotten and the Soldier slighted."