Sounds good, as long as it's tuned so that however many shots it does have is proportionate to how long it takes to reload.  I was originally going to have it take a certain number of turns no matter what(unless you roll a twelve) but if it's just one shot, I'll have it be a pass fail, something like half the time it succeeds, half the time it fails.  And a 12 means it succeeds and can fire again that same turn.  A two and I accidentally make a spark while reloading and blow the gun up?