That's why I think a lot of firearms owners who know a thing or two don't obsess too much over not having select-fire. If the balloon goes up and the zombies come out, I have a suspicion there'll be a lot more machine guns in civilian hands out there than what is listed in the NFRTR.
Select-fire outside of a combat situation is a whole lot of fun, but of limited utility. Even if FA guns were Title 1 items, I don't think people would "rock and roll" too much since it's just turning money into noise for the most part. A friend of mine has a legal M16 and realistically he just does little bursts with it. Mag dumps on happen when he has friends come to the range with him.
However, just because it is of limited utility doesn't mean it should be restricted. If a firearm can handle having a select-fire option, I think it should be there.
There are few guns left that can easily be converted to full auto without having lots of specific, legally incriminating parts already on hand. The idea of converting your semis to full auto if the crap hits the fan isn't practical unless you plan on having FA parts lying around, which I think is inviting trouble. While it's not necessarily illegal to have those parts (especially seeing as how they often come with parts kits), I think going out of your way to try and obtain them specifically would probably raise flags, as I imagine companies who sell them probably keep pretty close track of who's buying them. Definitely not advisable.
Of course the net effect of this is that it's easy to get FA weapons if you don't care about breaking the law, so any criminal who wants one would have no difficulty in obtaining it. In a world where you can order drugs online, I doubt they would have any difficulty getting those parts without leaving a paper trail, and then all it boils down to is a drill press. Even in a land where the government had waved its magic wand and made guns disappear, it's actually easier to make a full auto weapon from scratch than it is to make a semi auto one. Any idiot with an old mill could make a crude open bolt SMG out of stuff from the hardware store, whereas making it semi automatic would require someone with a much higher level of skill.
If the crap did ever hit the fan, I think you would see more converted weapons in the hands of criminal syndicates than in the hands of law abiding citizens. They already have the network in place to traffic in such parts, and their network would only grow stronger and more expansive in an economic collapse, whereas civilian sources for those parts (like Brownell's) would be instantaneously unavailable. Even if ecommerce did somehow stay online for a period of time (which I don't see being possible in any real SHTF scenario), they would sell out in no time and not get resupplied. More than likely, previously legitimate supply chains for those parts would then be rerouted to the black market.
So yea, I wouldn't expect civilians to come into possession of FA weapons in a SHTF scenario, but I would fully expect to encounter gangs armed with them. I would also expect gangs to come into possession of military and police stockpiles, so I think you would see more stolen military weapons than converted ones actually. Either way, you gotta love these great laws congress comes up with. No matter how you cut it, they always ensure the average criminal is more well armed than the average law abiding citizen.
