In the early 1980's, I had a Spanish-made Zabala 10 ga. side by side that would kill from the front & cripple behind. It weighed around 11 pounds and even with that much weight, it would pound my shoulder to a pulp. I used it waterfowl hunting. It would absolutely rake ducks & geese out of the sky. I made the mistake of pulling both triggers at the same time just once...four geese fell when both barrels blazed though...it also rocked me up on one leg. I used 4's for ducks and BB size shot for geese. The heavier shot really increased effective range and eliminated the number of wounded birds that would have to be chased down & finished. I sold it to a friend's brother and he used it very successfully deer hunting. Never shot a turkey with it though.
I've moved away from shooting magnum shells out of single shots, double barrels, & pumps in the last several years to ease up on felt recoil. a 3 inch 12 ga. is plenty to do the job on a turkey in range.
Luck Counts, good or bad