Without having the rifle in hand, these deals are tough to diagnose. On the model 70's, here's a couple things I'd check:
-Make darn sure the bolt nose isn't contacting the barrel. If it's close, it can touch when the back end up the bolt moves up when it's cocked. .007-.010 would be what I'd want back there. If it's a non coned bolt 70, make sure the counterbore dimension has adequate clearance as well.
- If it's a center action screw Model 70, loosen the action screws, pull the barrelled action out and put it back in with just the f-r screws. Then very lightly just snug the middle screw enough so it doesn't fall out.
- If it's bedded, make darn sure there's clearance between the bedding and back receiver vertical ledge ahead of the tang and behind the rear cross pin hole. If it's touching there, you basically have two recoil lugs...not good. Make sure the lug isn't tight against the sides or bottom. The only contact should be at the rear.
If all this seems right, I'd screw the original barrel back on as a 'control'. -Al
