When I took the scope off that was on it, I noticed when I shouldered the rifle that the flats on the top of the bases weren't aligned to each other. Whoever had installed the scope just cranked the mounts down and pulled the scope into place. The scope was a 1970's era Redfield 3x9. I believe one mount was a 46S, and the other was a 45S. I'm not working at home, so I don't have them in front of me now. The rear mount has a very close asymmetrical screw hole spacing, with one screw through the cross slot, while the front mount has evenly spaced screw holes on either side of the cross slot. There were no shims under either mount.
I'm making an assumption that when BSA sporterized these actions that they ground the rear receiver correctly. The rear bridge is where the BSA logo was placed (BSA inside a wreath, not the stacked rifles), over the tightly filled oval slot. The work is good looking. You can only see the plug because it blued to a dark blue-black, while the receiver is kind of purple blue, like an old Ruger Security-Six. If the rear bridge is correct, the front mount is slightly rotated to the left, looking from the rear. I leveled the receiver in a machine vise, and the used the flat bottom of the receiver as a reference point. I then placed small Starrett levels across the mounts. The rear mount level's bubble was in the middle, while the front mount level's bubble was off to the right, leading me to think the front mount is rotated to the left.
I then installed the scope mounting screw jig. It's the type that has two thick plates along the bottom of the receiver, a machined rod that goes down the center of the action that has two stand-off bushings, and a top plate that fits to the stand-offs. This has drill bushings where the holes are to be drilled. Two long 1/4" bolts go through from top to bottom that when tightened up bring the rod to the apparent center of the action, and tighten the whole thing in place. When looking down through the holes the drill bit bushings go through, the existing holes are not centered, but 3 of 4 holes are 1/2 a #6 screw hole diameter off in different directions, both front-to-back, and side-to-side.
I would like to fill the holes, and re-drill them correctly if possible. This is my first project that wasn't a straight barrel swap on a Remington 700, or re-barreling a Garand. Is tig welding the screw holes the only option I have? I bought this rifle for this project because it already had some of the work done, but it's not working out with the scope mounts.
-Byron