I'd try low brass at closer range to save the shoulder, like twenty yards, with your turkey choke tube in. Shoot at a small dot or mark on large piece of cardboard. Leave gun in the rest, and put red dot back on the aim point. Adjust left/right and up/down to where the center of the pattern hit.
Then move to 40 yards and repeat. Once locked in try the turkey loads and make any fine tune adjustments.
My
Bill.