Once at fire-arms training for my first police academy (don't ask- I put myself through school then got hired by a PD that sent me through their academy) a good-ole-boy who is probably still and will be forevermore a Mall Ninja brought his trusty Mossberg Tactical Deathspewer, a VERY short barreled 12g pump gun with a pistol grip, no stock. Everyone else had standard stocked SGs, either 870s or mossbergs, with barrels from 20-28". He was blathering on about how this was a great CQB weapon and yadda yadda yadda. The old timers just nodded and smiled.
We did a few courses of fire with pistol, then did a fairly lengthy session with the shotgun, to 'acclimate' us to the weapon. We noted that towards the end the Mall Ninja wasn't maintaining a very good continuity of fire, but he was no longer running at the suck, so we counted this a Good Thing.
We then broke for lunch, and when we came back, and he had traded in his Deathspewer for his hunting shotgun. We never saw the PG-mossberg again.
Mike