At one point, I put a commercial pistol grip in my 18" Mossberg 500, 12ga. At that time, the rear of the pistol grip fixture was a piece of steel channel iron. The shoulderless "push-pull" hold on the gun was tolerable, but not real
useful. Sneaking up on the gun trying to sight down the barrel got me hurt; that's the second most interesting scar on my left eyebrow.
My opinion is this: no matter what your barrel length, you should have a stock. Youtube is full of videos that show the unintended consequences of uncontrolled recoil.
Shotguns are fight stoppers, no doubt. Once you get to the range with your extra short kaboomer and start hitting steel with slugs or shot, some things might come to mind:
Could I get this job done with less recoil?
How can I put better sights on this thing?
What about stray pellets if I need a precision shot?
If I hadn't gotten such a short barrel, could the mag have more rounds?
If you like shotguns, you like shotguns,(which I do!) just sharing some experience.