Pictorial of lapping my scope rings, critique away.

D

DOUG DOTY

Guest
Went out to the race shop this evening when we got back from the Louisville gun show. " May be the last of it's kind if Obama gets his way......." Anyway, I fired up the lathe and made a mandrel that represented the scope tube diameter when adhesive backed sand paper was attached. I then found where the rings needed to be fitted on the reciever to get the desired eye relief and locked them down. Using the mandrel and a combination of rotary and linear strokes I lapped in the bases to be straight. As You can see they needed it, just as I was advised. I really doubted it from looking everything over with the scope just laying in the ring lowers and inspecting but you just can not tell like that. Here are a set of 4 pictures as I brought them into alignment. The rear was a little worse than the front but not a lot. I'll keep working this evening but here is the first hour into it documented.

Doug...

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You might want to get a small container of the lapping compound from Sinclair's. It will give you a bit better lap-in than the paper and it's cheap.
 
It looks like it worked..

I use 120 grit abrasive I bought from Brownell's about 30 years ago and a round lapping rod of the appropriate size.

... Or I use Burris Signature rings...
 
Done for now, I want to test fire at the range for scope "0" and then will pull it apart and maybe do the upper rings while I am loctiteing it all in place. kinda seems they would find thier way while torquing them down with the 4 independent screws per ring. ??? You can see the mandrel in this last picture, I spun it up on the lathe out in the race shop to be equal in diameter to the scope when it had the sand paper on it.


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Top ring halves do not need lapping... all they do is hold the scope down on the already lapped surfaces... and none of it needs Loctite...
 
Was just turning in for the night, After thinking through it I don't see the ring uppers as even plausable to lap as it would be impossible to get them back into the same position as when they were being lapped when re-installing with the scope. They will find their own way.

Thanks, maybe I am done with this scope mounting deal
 
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Ring lapping critique

Doug,
Just a couple of suggestions as to how I would do that job. Cover the port with a rag so that no pieces of abrasive get into the ejection port. If a small particle or two managed to get in, when your bolt was inserted, it could score the internal raceway. I stand corrected, I see you've covered the port with a paper towel.

After I lap my bottom rings in, I remove all the compound and fasten the top rings down securely onto the lapping bar. This forces the rings to conform or 'set' to the lapping bar od., thereby protecting the softer aluminum of your scope tube. I then match mark the top halves of the rings with the bottom halves with a centerpunch on the inside where the screw holes are; making them invisible from the outside. You now have a matched set of rings. I then take a tiny drop of Locktite Ultra Blue and place it in the middle of the saddles on both lower rings and move the scope tube to distribute a very thin coating evenly around the ring bottoms. Center your reticle, adjust the eye relief and then install the top rings. My verticle reticle is set to the string on a plumb bob approx. thirty yards away in my basement with the receiver firmly levelled and clamped in a padded vice. As I tighten down the top rings I can observe any tendency for the scope to roll and compensate by tightening the opposite side screws, front or rear, to keep my reticle plumb. That's how I do it. I also use about a 320 grit aluminum oxide lapping compound but your method still accomplishes the job.
Chino69
 
Pal the paper is too thick and will unnecessary enlarge the ring size. Chuck away the paper and use a fine lapping compound.Rad
 
Rad Mrdal said:
Pal the paper is too thick and will unnecessary enlarge the ring size. Chuck away the paper and use a fine lapping compound.Rad
Click to expand...

As stated above I lathed the mandrel for a perfect fit with the paper on it.... I would think this is better than trusting some bodys kit to match your scope and being restricted to to that diameter and using only lapping compound. ???
 
Doug, I agree with the way you did it with paper. I have a bar I made under size twice the thickness of the paper and it works very well. It is much faster than lapping and the clean up is easier.
 
It did work top notch but you kinda need a lathe in your shop to do it...
 
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