As an example of how much difference the autoloader makes, I used to weigh 110# soaking wet. Dreaded shooting 12 ga with buckshot. But a friend who is a manufacturer rep has a Benelli police autoloader. Man that thing is FUN. I could chase milk jugs all day with that cannon!
Another tip- square your torso up, relative to the target. When practicing with shotguns and followup shots, you want that deep pocket in your shoulder to make a U with the sides pointed toward the target, not off to the side. Then the recoil is aimed at your clavicle, NOT the rotator cuff and stuff at the point of your shoulder.
Picture your feet keeping the usual K stance, with your R leg set back, wide and at a 45 to your line of sight. Rotate at the waist until your shoulders are at a R angle to line of sight, square to the target. Not only does your shoulder take less beating, your waist and whole torso absorb more of the energy and naturally help bring the gun back on target between shots.