The simple truth is that short rifles and short shotguns were never a problem, and continue to not be a problem today. The 1934 National Firearms Act originally wanted to restrict handgun ownership, and the clauses relating to SBRs and SBSs were simply to close the loophole of a person cutting down a rifle or shotgun to get around a handgun prohibition. That handgun (effective) prohibition was removed before the legislation was passed, but the SBR/SBS parts were left in. And thus for 89 years we have has the ridiculous legal situation in which a handgun is fine, a long gun is fine, but something in between is prohibitively regulated.
One major change to the NFA came in 1968, when the minimum legal barrel length for rifles was dropped form 18 inches to 16 inches. Why? Because the government had already sold a quarter million M1 Carbines – with illegally-short barrels – to private citizens, thus rendering them all felons. Instead of trying to enforce a clearly irrational law, Congress reduced the barrel length stipulation.
With this issue once again coming to a head over pistol braces, it is time to finally solve the problem and end this nonsense. Short barreled rifles and short barreled shotguns (and AOWs) should be removed form the NFA entirely. Their regulation is a waste of law enforcement’s time and a massive bureaucratic burden on individual citizens, who are faced with felony convictions and 10 year prison sentences for utterly harmless actions.