Putting a custom aperture sight on a mauser 93 .. looking to mount it on the bolt shroud. Problem is this wobbles even when cocked. Thinking I should TIG the shoulders where they ride on the action to eliminate wobble. Anyone know of another solution? (Cocking piece does not wobble but it fires flush with shroud so mounting sight there Rigby style is not straightforward either).

Yes, do that, and weld on an extension on the rear of the cocking piece and put the Rigby peep on that.