I agree.....................I've set the tone a few times on traffic stops with a carload of dirtbags with a shotgun. Rack that thing and you tend to get some peoples attention.
Nothing triggers your butthole's pucker response quite like a shotgun rack that's for sure!
I am on the bandwagon on the sound for sure, nothing like hearing that slide to let everyone know that it is time for everyone to pay attention. Go with the pump shotgun, the sound alone may solve the situation without having to clean the carpet.