@Cycloptichorn,
Yep, one shot, one kill. Of course, it would help if they were to stand still. Out in the open. With a bullseye painted on their chest.
Actually, after dropping one or two of them, I would expect the others to turn tail and run thus saving me from having to reload. But I digress.
And yes, Cy, carrying clips for reloading is easier than carrying multiple weapons and thus a law such as suggested would make things tougher. But as you say, someone determined to kill as many as possible will find a way. As an aside, though not germane to this discussion, is that had there been others at the event carrying weapons, he may well have been dropped before emptying his first clip, which also would have limited the killing. Just saying, ya know.