First, do NOT get a pistol grip for the shotgun. Worse accessory choice EVER! Leave the shoulder stock like it is. Weapon light? I'd skip that too. Turn on the light switch. Don't know why anybody'd be walking around their own house with the lights out and a weapon light on their gun. Spend whatever money you would have spent on a sidesaddle, weapon light, and pistol grip on some ammo. Buy the WalMart birdshot and shoot it until you're tired. Then do the same thing the next day until you run out of money. You ain't gonna wear the Mossberg out.
Finally, buy quality buckshot loads. Slugs are for mall-Ninjas or operators with lots of experience. It'll go through the bad guy, through the wall, through your neighbors wall, and through a good guy in your neighbors house. I'd limit yourself to a magnmum load, but I prefer 2 3/4" magnums. They have 12-pellet 00 Buckshot loads. Get Winchester or Remington, don't buy cheap ammo that you're going to bet your life on. Many choose #4 buckshot and I'm okay with that choice as well. You don't need 3" magnums. They give you 3 more pellets, but they are travelling slower so penetrate less than the 12-pellet 2 3/4" magnum loads.
Every range session, I'd light off a box of the Buckshot (5 rounds) so you know your gun will cycle them and you're familiar with the recoil/blast impulse. I store my shotguns hammer down on an empty chamber, safety off, and magazine full. No sidesaddle, no pistol grip, no flashlight, and no sling. In a tense situation, turn on the lights and pump a round into the chamber... you're loaded and the bad guy know's you're there, knows you're armed, and will now either confront you and die, run, **** his pants, or do some combination (actually, most of the time they will do EXACTLY what you tell them to do).
