A couple of questions if I may..

out deeper. It in effect allows you to screw down the die farther which pushes the shoulder back a little bit. We are talking a few thousandths here, not much.

As I mentioned, I have removed material from the bottom of the die body that allows the same thing.

I have not measured various shell holders, Lyman, RCBS, LEE, Hornady of the same size, but it figures there could be variations. Small amounts can be just enough to give us issues. Also make sure you lock the die once set, they can back off. Progressive presses and turrets can be springy and add to the problems.

The other guns usually have a dovetail or sight humps to serve as a "recoil stop". The sight and mount try to remain in position as the gun literally kicks out from under it. In this instance the mounting screws would need to bear the forces. He makes every mount for the specific application. I'm sure he could figure something out.