Before I shim, I bore sight to a target and shim with masking tape until the a scope is in the middle of it's vertical adjustment range. While I am doing that, I check that the scope bore sights to the middle of the horizontal range too, in case that needs correcting.

For two piece Weaver mounts, I make narrow shims like dams for the epoxy I glass bed the mount to the receiver. The epoxy must cure with the mount screws loose and the mounts held in alignment.
A scope with rings that are correctly spaced and rotationally aligned makes a good alignment fixture for the mounts while the epoxy cures. It is not easy to get the rings on the scope right. After the epoxy hardens, I take off the scope with rings and tighten the mount screws to the receiver.

That way I don't have to lapp the rings, and scopes can move from rifle to rifle, taking their rings with them.

I don't know anyone else who does this, but I don't know anyone else doing anything like moving a 40X Leupold to 4 different surplus rifles while at the range.

I glass bed the scope in the rings with JB Weld, after lapping them. Sure removes all stress on the scope tube, and eliminates ring marks.
Don

That's been my standard way of mounting scopes for at least 12 years. I don't do it quite like you but it amounts to the same thing. I will remove metal from the high mount to help things along in centering the focal plane BEFORE I do the mounting. I also epoxy the screws at the time I epoxy the bases and afix the whole thing to the receiver. I use a few Leupold QRW rings for the scope swapping between rifles.

I used jb weld on the rear base on a mauser that had an ill fit and then redrilled and tap the holes. i needed to gain some heighth so i installed a .075" shim and jb it to the rear base and it came out just right. i used a scope and a bore sighter to aleign the rings. I use the burris z rings and they come off and go back on the money .

I did the same with mauser that was a very ill fit. I glass bedded the mounts and it shoots very well now.