I had a Mossberg 500 for 10 years and put over 2-3000 rounds through it without any trouble. 18 inch barrel with the pistol grip fore and aft. I dont see why you would be worried about a choke with something like this as its for close combat and if you want a tight shot group just go with 3" magnum slugs.

If you want something to be guaranteed lethal use bird shot. The person will bleed out because there are far too many holes for even the best trauma team to fix. I always alternated loads, first round was a slug then bird shot then 00 buck this was off advice from a few deputies in the family.