Scope mounting help.

[Addicting]

My hunting partner was having issues sighting in his rifle. This is a new 280ai build off from his grandfather’s pre 64 action. I had loaded up a hand full of various pulled bullets to do the rifle break in. It didn’t surprise me too much that the didn’t group well.

I got the rifle yesterday to measure the lands and do some testing. First shouldering of the rifle I could tell the scope was canted. After some disassembly I found out what happened. The front and rear rings are not level with the center line rifle.
Rear ring level:


Front ring:

How much it was canted:


The scope was originally mounted based off from the cant of the front ring. When you shouldered the rifle you could see that the cross hairs were canted right away. Mounting the scope based off from the rear ring being level makes the cross hair appear vertical when shouldered.

My guess is the only fix to them being so far off is: Rebore the receiver’s threads to 8-40 so they are in the centerline of the action?
Or will it be ok to just mount it level and use it? It didn’t appear to be torquing the scope tube when it was set in and snugged down.

Anyone else have any ideas?
@BcGunworks

 

[MThuntr]

personally that would drive my gun OCD into overdrive. I'd have the mounting holes filled and redrilled.

 

[antelopedundee]

A Picatinny base might fix it. Any idea how far the scope is off from properly lining up with the bore?

 

[ZBB]

I’m gonna try my best to ask these questions on what I’m thinking so bare with me. Are the receiver threads centered and the front holes not perpendicular to the action? Or are the front holes off center? If they’re both centered why not just lap the rings and level off the rear?

 

[noharleyyet]

Re-tap....that 2nd pic made me wince.

 

[Fire_9]

What issues was he having sighting it in? Running out of adjustment? I would stick some alignment bars in there to make sure they’re straigh with each other.

A lot of people are going to perceive a scope leveled to the action as being canted too because not many of us truly hold the rifle level. People get really hung up on having their scopes level to the action and it really doesn’t make any difference in my mind. Level the scope to how you shoulder the rifle and be done with it.

 

[Addicting]

A Picatinny base might fix it. Any idea how far the scope is off from properly lining up with the bore?

No idea.

I’m gonna try my best to ask these questions on what I’m thinking so bare with me. Are the receiver threads centered and the front holes not perpendicular to the action? Or are the front holes off center? If they’re both centered why not just lap the rings and level off the rear?

It appears that that just the front ring is off center from what I can tell. I don’t have alignment bars to verify it.

Re-tap....that 2nd pic made me wince.

After I showed what I found to the owner he agreed it needed to go back to the Gunsmith to have them recut.

 

[Addicting]

What issues was he having sighting it in? Running out of adjustment?

He wasn’t shooting at paper, he was just trying to break the barrel in. From what I understand he used those first ten rounds into the dirt in a sand pit. He just said he couldn’t hit whatever he was aiming at. But like I said that didn’t surprise me, those rounds where never loaded to hit anything. They were all marred up junk bullets I saved for break in.

 

[Fire_9]

There’s a chance that it could just be the rings too. Swap the rings front to back or just flip the front one 180 to see if the results are the same

 

[Addicting]

There’s a chance that it could just be the rings too. Swap the rings front to back or just flip the front one 180 to see if the results are the same

I wondered that as well, I gave it back earlier today. It’s headed back to the Gun Smith tomorrow.

 

[noharleyyet]

I wondered that as well, I gave it back earlier today. It’s headed back to the Gun Smith tomorrow.

Update when you can...I'm guessing the pre64 had tap tolerance issues...maybe drilled out of plumb to the center line on the front.

 

[antelopedundee]

No idea.



It appears that that just the front ring is off center from what I can tell. I don’t have alignment bars to verify it.




After I showed what I found to the owner he agreed it needed to go back to the Gunsmith to have them recut.

A Picatinny base may not be in alignment with the bore, but the rings [if you would use the Weaver style] will certainly be in alignment.

 

[Addicting]

Update when you can...I'm guessing the pre64 had tap tolerance issues...maybe drilled out of plumb to the center line on the front.

The serial number made it produced around 1954. We are wondering if it even came with the tapped holes. Thinking his grandfather may of done it in his “shop”.

 

[Blaser270]

There’s a chance that it could just be the rings too. Swap the rings front to back or just flip the front one 180 to see if the results are the same

Ok hear me out. If the front holes were misdrilled, that is, not quite at the 12:00 position, the ring would be off of 12:00, and the a is of the front ring would not be aligned with that of the rear ring. That would be the only way for the front mount to be so far off level as compared to the rear ring. And if that was the case, the scope wouldnt even come close to sitting properly in the rings without damaging it when the rings are torqued. Is it possible that the one ring is mis-manufactured? Hear me out. The mount holes may be within tolerance at the 12:00, but if one ring is cut incorrectly, it would be “off level”, the split line would be not quite “flat” when its mounted to the gun, but the axis of the scope may still be nicely aligned. Its the axis of the scope that’s important, not necessarily how level the ring halves are. Make sense? Or am i out to lunch?

 

[Curvebow]

I would first try other rings. If the holes in the receiver were not at “12” o clock, then the scope would be pinched in the rings. You say the scope was canted, that’s simply a matter of loosening the rings and aligning the scope properly.

i have wheeler engineering leveling tools and one of them works off the flats that the bolt uses as I believe the model 70 to be a 2 lug design. I think it’s the talley ring/base combo. As others have suggested, try reversing the one in question to see if it improves or remove them and get a picatinny rail & separate rings. One big advantage of the rail is that it provides a great level surface to get the rifle leveled before installing the scope and leveling the scope (try using the flat under the adjustments for a true level).

Then bore sight the gun when all is done and the try shooting it at close range like 20 yards, adjust the go longer... good luck...

 

[antelopedundee]

Ok hear me out. If the front holes were misdrilled, that is, not quite at the 12:00 position, the ring would be off of 12:00, and the a is of the front ring would not be aligned with that of the rear ring. That would be the only way for the front mount to be so far off level as compared to the rear ring. And if that was the case, the scope wouldnt even come close to sitting properly in the rings without damaging it when the rings are torqued. Is it possible that the one ring is mis-manufactured? Hear me out. The mount holes may be within tolerance at the 12:00, but if one ring is cut incorrectly, it would be “off level”, the split line would be not quite “flat” when its mounted to the gun, but the axis of the scope may still be nicely aligned. Its the axis of the scope that’s important, not necessarily how level the ring halves are. Make sense? Or am i out to lunch?

If you can find a Picatinny base that will fit, the ring alignment issue will be eliminated. But you will find out how far off of alignment that your base mount holes are.

 

[antelopedundee]

No idea.



It appears that that just the front ring is off center from what I can tell. I don’t have alignment bars to verify it.




After I showed what I found to the owner he agreed it needed to go back to the Gunsmith to have them recut.

You could have tried bore sighting the scope. Remove the bolt and look at something like a vertical post through the bore. Without moving the rifle, turn the windage dial until the vertical crosshair aligns with the post. Make note of how much you have to turn it.

 

[Addicting]

You could have tried bore sighting the scope. Remove the bolt and look at something like a vertical post through the bore. Without moving the rifle, turn the windage dial until the vertical crosshair aligns with the post. Make note of how much you have to turn it.

That had been done prior to him getting it back from the Gun Smith and then shooting it in the pit. Between that, him not hitting anything, and the front ring being off center, I chose just to send it back. I will update with what the Gun Smith has to say after he talks to him today.

 

[Addicting]

Ok hear me out. If the front holes were misdrilled, that is, not quite at the 12:00 position, the ring would be off of 12:00, and the a is of the front ring would not be aligned with that of the rear ring. That would be the only way for the front mount to be so far off level as compared to the rear ring. And if that was the case, the scope wouldnt even come close to sitting properly in the rings without damaging it when the rings are torqued. Is it possible that the one ring is mis-manufactured? Hear me out. The mount holes may be within tolerance at the 12:00, but if one ring is cut incorrectly, it would be “off level”, the split line would be not quite “flat” when its mounted to the gun, but the axis of the scope may still be nicely aligned. Its the axis of the scope that’s important, not necessarily how level the ring halves are. Make sense? Or am i out to lunch?

I wondered about this as well. The scope didn’t feel like it was binding and set in the bottom of the rings pretty well. Unfortunately, I had already returned the rifle back to him when that thought struck me. I will update the thread with what what we find out.

 

[antelopedundee]

That had been done prior to him getting it back from the Gun Smith and then shooting it in the pit. Between that, him not hitting anything, and the front ring being off center, I chose just to send it back. I will update with what the Gun Smith has to say after he talks to him today.

Far be it from me to criticize a smith, but if you try to bore sight a scope and use up half of the windage or elevation adjustment, something is WRONG and it should have been fixed before giving it to the customer.