How about a gun called the 'Muthur-Sucker'. It fires a grenade type projectile which sucks nearby objects and organisms into a singularity and crushes them, like a sophisticated Black Hole. This would last for about five seconds before exploding, sending debris that wasn't quite sucked into it in time flying (if you've played 'Castle Clout' you know what I'm on about). Well, either that or a Wabbajack gun.