I have had 3 back surgery's and looking at a shoulder soon and all I can say is don't shoot slugs out of your 12g!
I wanted to sight in my 12g and man was that the wrong thing to do with a iffy shoulder!
If you shoot AR's get a conversion or dedicated upper to shoot .22lr. No recoil and you still get trigger time on your AR. Same goes for some pistols that offer conversion but, if you reload you can make some pretty mild pills.