Just because I can do something, does it really make sense to do it?
Well, that's really the question, isn't it? If you're imagining someone defending their home with an MG-42 set up on a tripod in the hallway, I'd probably agree that it doesn't make much sense, and the circumstances of that shooting are going to, rightfully, be investigated with extra scrutiny.
But regarding more common NFA items, what are the benefits? What are the costs?
I, personally, see very -- very -- little benefit in using almost any full-auto weapon for home defense. It just isn't necessary. It isn't
better than a common shotgun or a handgun that you are proficient with. (Unless, of course, it is actually THE weapon that you practice with most and are most proficient with. I don't know many (any) shooters who can honestly say that.)
(By that I mean, I can meet or exceed the cyclic rate of some submachine guns with a service sidearm, and put every round into the "A" zone of a target at common defensive distances. Switching to a submachine gun wouldn't improve that -- even if all other things were equal, which they obviously really aren't.)
SBR, SBS? I see no detriment and some concrete benefits to using a shorter long-gun -- again,
if I've practiced with it a lot and use it as well as any other defensive arm. There is no possible way for a prosecutor to claim I've recklessly endangered anyone with it MORESO than if I'd used a standard-length arm of similar design.
Silencers would seem to just make sense. "
I use this device because it protects my hearing. I leave it installed on my weapon(s) at all times. It was on the weapon when I retrieved it upon hearing the door to my house being kicked in, etc." Again, only benefits, no detriments.
If a prosecutor wants to bring up the "evilness" of your NFA-regulated items as a significant point in your trial, I'd imagine any defense attorney worth his fee would be able to hand him his butt for wasting the court's time with such an obvious non-issue.