250 fps is on hell of a nerf if you ask me. Even pneumatic guns can definitely shoot over three times that speed, not to mention gunpowder firearms. Though i suppose realism isn't of great importance to the tournament, but there is more to my complaints than just that.

 If not the size of the bullets, they would be visible to the naked eye at such a speed, thus, able to be dodged just as an arrow. Taking in mind that quite a few characters will have [i]enhanced[/i] vision, even if bullets retain their destructive properties, gun users may be at a disadvantage. And on top of that, i imagine most would be able to stomach multiple bullets even, as long as the gunner doesn't hit a vital area. Which, of course, becomes a pain in the arse to accomplish with such slow projectiles.