One reason you see more Mossberg over Remington shotguns used in Shortbarreld shotguns is a tax issue. If the shotgun came with a stock, it is a SBS(short barreled shotgun) which means a $200 tax stamp. If it came as just a receiver or pistol grip shotgun from the factory, it is considered an AOW(any other weapon) which means $5 tax stamp. Crazy!!
You don't see much in the way of straight shotgun receivers coming out of Remington.