Re: off center reciever holes
I have repaired a number of receivers with the scope mount holes drilled off center.
I have tried TIG welding up the holes and re drilling and re tapping. Sometimes weld metal can be hard to drill. It gets the receiver hot.
I have tried re drilling and tapping somewhere else. This is known as "The Swiss Cheese Solution".
These days I prefer to modify the front* Weaver mount [known as "modify the cheapest part"]:
1) Move over the center of the concave radius on the bottom of the mount with a boring head. I use modified V blocks to hold the scope mount in the mill vise.
2) Waller over the through hole(s) in the Weaver mount with the right sized small end mill, making the hole oblong.
3) Waller over the countersink(s) in the Weaver mount with the right sized small end mill.
4) Fixture the scope mount on the receiver with a scope and Weaver rings. Bore sight with a scope that has had elevation and windage adjusted to have the reticle in the center of the scope tube. Use highly viscous epoxy between mount and receiver, with release agent on the loosely screwed in screws.
5) When epoxy hardens, remove fixture and release agent from screw and tapped holes in receiver. Toque screws to clamp the mount to receiver with Loctite 242.
This then maintains my standards of "scope with rings swapping and still being on the paper" and "no ring lapping allowed".
* The recoil stresses on the rear scope mounts are static, shear, and tension, but mostly only static and shear on the front mount. The wallered over hole and countersink leaves less bearing area for the screw head on the mount. The static forces are tested at installation, but the recoil tension forces are added in the field. It is best not to subject the compromised interface to the additional tension.
