DOC, the standard stock is built for Joe Average, a 5'8", guy with about a 32" shirt sleeve. Shortening the stock may result in better fit to you and a little,repeat little, less recoil.
Turkey loads can loosen fillings, with their heavier payloads. Bench or pattern test with lots of padding. I've a wearable shoulder pad here(nicknamed the Wonderbra) I use when benching/zeroing slugs.
Coupla other ideas...
You use a mag plug when turkey hunting, I guess. Get a plug made from solid brass or steel and install it.That'll raise the weight enough.
And, spend maybe $50 and get the forcing cone lengthened. This shortens the pressure spike and lengthens the time of the peak push, so to speak. It also improves patterns, important for Gobbler busting.
Two 3" turkey loads runs about 5-6 oz. Keep two in the mag for that extra weight. Fast followup shots aren't that crucial.
If you reload, try loading an empty w/o wad or powder, just fill the case up with the smallest shot on hand. crimp and epoxy.That can serve as more weight also.
One thing about Turkey loads. When I tested some out a while back, the two that gave the tightest patterns in my 870 were a 1 5/8 oz Remington Duplex 4X6 and a 1 1/4 oz Winchester #5 shot,2 3/4" load. Close to identical numbers of holes,and that #5 load was a lot easier on me.
Hope this helps...