I haven't given it a whole lot of thought. The existing arguments I've made can extend to the bigger, more powerful guns, but the argument gets somewhat weaker. If machine guns are illegal, then the government would have less trouble subjugating people who only have handguns. But that's pretty weak. I'd rather have a handgun for defense anyway.
Machine guns are also very inaccurate, since there so hard to control.
I wouldn't be against more strict regulations on the bigger guns. By regulations I mean more strenuous licensing and training required to use them. I don't think there as valuable for personal self-defense, which more of my argument rests on. But when they know people don't usually have a gun, they will feel less threatened. In general, though, there's a large disincentive to try to mess with someone who is armed as well.