I would settle on a cheaper pad too. I just looked at the 500 series and the 930 which comes with either porting or a muzzlebreak. In heavier loads, you get not only recoil to the shoulder, but muzzle jump as well which affects accuracy too. And the lighter the gun, the less mass there is to absorb recoil. I might investigate some sort of break.

That said, even my really seasoned shoulder does not shoot slugs well. I recently saw a personal defense program that showed slugs vs. buckshot vs. birdshot and the damage each does at different distances through walls, etc. I'm going to arm with 1-1/8 oz of 7-1/2 shot. Given my house size and set up, I can't risk sending a slug into the neighbor boys' bedroom.