Mossberg makes their 500 pump in a version that comes with both a pistol grip stock, and a shoulder stock. You can try both. I can all but guarantee you after shooting a couple of boxes of high performance 12 gage loads through it with the pistol grip attached, you'll put the shoulder stock back on and leave it.
Mossberg also makes a "Combo" platform in their 500 pump. It comes with both a 18" cylinder barrel, as well as a 28" Modified choke vented rib barrel. It makes for a much more useful package. You can leave the 18" Cylinder barrel on for a "house gun", and switch to the 28" Modified choke barrel for any type of bird hunting. This gun is chambered for 3" ammunition which makes it even more useful. From bad guys with slugs or 00 buck, to Grouse and Pheasant with low brass upland loads, to waterfowl with 3" Magnum loads. Not a bad deal for $200.00 and change in todays sick economy.