scope mount holes drilled crooked

Rick65Cat

Rick65Cat

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Just put an NOS barrel and receiver on my 6.5x55 that was bought years ago. It was already drilled and tapped for weaver mounts when I got it. I finally got around to mounting a scope and tried to "rough" sight it in with a grid bore sighter you magneticly attach to the end of the barrel. I cranked the windage screw as far as it would go and it still wouldn't center.
Now, maybe the bore sighter is wonky but its a Busnell and I'd hope its fairly accurate. I'm taking it to Gennesee today to sight it in and break in the barrel and get a group pattern.

If,...the holes aren't drilled in line with the barrel, How can I correct it? I was thinking about a shim (a sliver cut from a soda pop can) epoxied to one side of the mount and CAREFULLY sand off the equal amount on the opposite side. That would shift the scope over about 10 thousands of an inch (or however thick a soda can is.)

Thoughts?
 
remove your rifle bolt, pick a sharp reference point 100m away and center the bore of the rifle on the sharp point. adjust your scope to match the view. Do you get the same result as your magnetic boresighter? if no, trust what you can see. if no, could be your muzzle isn't cut square or has some imperfection that deflects slightly the angle of your boresighter. Do you have a dial caliper? even an accurate ruler. measure the width of the receiver at all 3 or 4 drill holes and find the centerline of the receiver mark it with tape and see if your scope base holes are all in a straight line. sometimes one is off. if the holes are truly out of whack, you may need to have them redrilled.
 
Instead of trying to make some shims I would first try a set of the Burris Signature Zee rings with the insert offsets shims. Those will likely solve your windage issue without having to fabricate a 1-off mount. I have used the Signature Zee rings a number of times and they work great.
 
Did the "look down the barrel" at 100 yrds then the scope to get them to match. I was able to get the crosshairs close. By that I mean I was on the target paper (2 foot wide by 2 1/2 feet tall) I wasn't really interested in zeroing the scope as I will be doing reloads at a lower velocity. However I did shoot to get a group. 5 shots at 100 yrds with a 1902 receiver and brand new 23" barrel in a bedded military "sporterized" stock with a Bushnell Elite 3200 5x15x40 using Federal "Fusion" 140gr SP shells. I am super happy.

https://photos.app.goo.gl/R5fobdMA2ZjMSdqx5
 
There is also the leupold "twist in" rings where the rear base has windage, but if the holes are drill out of straight you also risk damaging the scope when you tighten rings down
 
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