I kill all my fall turkeys with 12 ga 2 3/4" copper plated 7 1/2s... the high power, high brass, Federals... I can find the exact name if you want... I shoot them out of my 28" modified Model 12. The recoil isn't bad and those loads are killers... The pattern is dense and also fairly large... it'd be good to 35-40 yards probably...
I shoot that arrangement so I can aim at the head of a flying turkey but it would also work great for a young kid who may jerk or flinch because it would give them a nice wide lethal pattern...
Hell you could pattern the gun with light 8s and then only shoot the hot stuff at turkeys... he'll never feel the recoil in a hunting situation...