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
![z-twocents :z-twocents:](https://oldgobbler.com/Forum/Smileys/classic/z-twocents.gif)
Bill.