You can't find success if you flinch every time you pull the trigger. Minimizing the effects of recoil are essential for learning to maintain concentration on the target and follow-through.
An experienced shooter can use low recoil ammunition to exercise a focus on fundamentals - not a sore shoulder. A new shooter, who likely fears recoil more than any other aspect of shotgunning, will be able to appreciate shooting without the pain.
12ga 2-3/4 inch
#7-1/2 & 8 lead
25 rounds per box, 10 boxes per case