So I should say pretty clearly that I think it's a very interesting idea, and I think that it provides a ton of chaos in a way more interesting than any fireball would, in that it encourages interesting role-play among the crew. But I think there could be a balance issue with it, in that a lot of the interesting role-play it would cause would rely on players being morally irresponsible. A lot of guns on the floor means nothing if ever player is terrified to death to touch one if it means a threat of ban, or would just mean a bunch of players are stuffing guns in their backpacks and then doing nothing with them. I think an issue with it is that it would seriously encourage players to self-antag.
Another, not so strictly bad problem with this, is that a wizard could summon guns only to be shot with one of his own by a crew who may have stashed one, which would be pretty rich but it could really end the round quickly.
I just think it would be way to much trouble, given the tight rules of the server would really put an end to any of the chaos that such a situation would naturally cause, negating the fun of what sounds like a really fun spell, at least for me.