First go at lapping in a scope

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bambuino

bambuino

Member
Aug 13, 2020
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HI, United States
This is a follow up to a previous post seeking advice on lapping compounds: https://www.airgunnation.com/topic/scope-lapping-compound-substitutes/?referrer=1

Here I present my first go at lapping in my airgun scope, using a set of Wheelers and some valve grinding compound found at NAPA.

Checking true of the rings...Note: The optional upgrade is purchaing this set of Wheelers in the protective case. As is, these are shipped in minimum of packaging and suffers dinging the points, seen here. Still though. can see slight misalignment.

IMG_8994sm_true.1610051081.jpg


Setup. A couple q-tip loads of compound was applied to the rod, with top of rings finger tight on fasteners. This compound is a bit clumpy, and once is spread evenly with a couple passes can turn down fasteners, again only finger tight, allowing rod to pass smoothly. I only gave a couple minutes slowly working this, as initial impression was of compound being bit on coarse side. Handle was passed and rotated in figure-8 pattern.

IMG_9005sm_setup.1610051863.jpg


First looksee. Both rings suffered similarly this slight CW misalignment. Believe I did not turn down top strap evenly on the fore and rear fasteners.

IMG_9007sm_ck1.1610052487.jpg


Skipping ahead a couple steps, and making some progress. Every so often, turning the fasteners down just a bit is required to make up for material removal and compound breakdown. Again, just only finger tight to keep rod even in rings, but not binding up the rod.

IMG_9012sm_ck3.1610052789.jpg


Fairly satisfied with this compound. Made a few more passes to get a bit more contact surface on the rings. Final dressing was done with a few swipes of crocus cloth to gently knock down the scratches and likes. For finding the optical zero, I built this little jig.

IMG_8996sm_jig.1610053547.jpg


There you go. Please submit your advices and criticisms below, as be much appreciated.

Best regards, Mark




 
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Thanks for posting. For future, get yourself a picattiny/weaver rails section and mount it to a 2x4 edge. Mount your rings to that, so you don't have to saran wrap your gun
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Thing is, solidly mounting the bases to the dovetail, torqued, loctited and all, guarantees for me, in my limited experience, that the rings are dedicated to that gun. Should I ever remove these rings, I feel I would need to re-lap after mounting on a different dovetail, same scope and all. I don't feel confident that lapping the rings to one rail for convenience sake will give me same end result when bases are then removed and placed on a different gun. I could be all wrong on that though.
 
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THATS THE MINIMUM WHAT EVERYONE NEEDS TO DO BEFORE MOUNTING THEIR SCOPES!!!
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Right, right...was not on my mind at the get go. The ring marks on the tube cleaned up. Took a couple months to figure where I like this scope to sit. With lapping feel better about torquing the caps down to about 18 in/lb loctited, from the 10-12ish while I was tweakin it around.
 
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Thanks for posting. For future, get yourself a picattiny/weaver rails section and mount it to a 2x4 edge. Mount your rings to that, so you don't have to saran wrap your gun
Click to expand...

Thing is, solidly mounting the bases to the dovetail, torqued, loctited and all, guarantees for me, in my limited experience, that the rings are dedicated to that gun. Should I ever remove these rings, I feel I would need to re-lap after mounting on a different dovetail, same scope and all. I don't feel confident that lapping the rings to one rail for convenience sake will give me same end result when bases are then removed and placed on a different gun. I could be all wrong on that though.
Click to expand...

Fine job on the lapping! 

In theory, you could do a one-time lap on those one piece offset mounts with the solid base and clamping rail systems, as they should return close to the same zero each time removed and returned to the same place. I'd think it would stay true between guns so long as the picatinny rails were machined straight.

Nice holding fixture too! Did your kid wonder where all his Legos had disappeared to?
 
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Very nice right up. There's one important thing Id like to add to your right up. Tag the cap and bottom of each ring. To insure they stay together. Tag in such a way you'll know which ring is forward and which rear and the orientation of the rings. Now that your rings have been lapped together they need to stay as matched pairs. And forward will alwise being the same. If ever used on a different project, your laping could work agent you. Mixed matched lapped rings could be worse then rings that were never lapped in the first place.
 
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Very nice right up. There's one important thing Id like to add to your right up. Tag the cap and bottom of each ring. To insure they stay together. Tag in such a way you'll know which ring is forward and which rear and the orientation of the rings. Now that your rings have been lapped together they need to stay as matched pairs. And forward will alwise being the same. If ever used on a different project, your laping could work agent you. Mixed matched lapped rings could be worse then rings that were never lapped in the first place.
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Thank you. I did go sniffing around here for previous posts and some pics, prolly overlooked several, so posted something fresh.

Good point on marking out the mounts for orientation, particularly these single mounts. To illustrate the point, mis-matching these rings down the road could turn my nice scope into a banana. The gun is a bit overscoped, but I am so thoroughly pleased with this pairing that the two are just gonna have to get along for a while.
 
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@bambuino Thanks for these threads. I read through both and had no idea this was something that had to be done when I purchased my first air rifle. I “mounted” my first scope that came with the rifle. After a while I noticed that something was off with my shots no matter what I did. After a while I noticed that the space between the rings differed between the two sides of my rings (they shipped this way), so I started looking for info on scope mounting.Then I encountered unfamiliar terminology and didn’t know what it meant (words like “lapping” and “cant”), so I started reading more. In the process I found your posts and moved to YouTube videos. Your thread looks similar to what I saw gunsmiths on YouTube do in their vids. The fact that you documented your first attempt makes me feel that I can do it as well. The pics helped. Thanks again for sharing. 
 
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One of the reasons I like one piece mounts.
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This. Most one-piece mounts fix any issues from the get-go (most issues are rifle / mount related). If you're going to lap rings, you should bed them as well. Perma-Tex Black (Napa, or other auto parts store) works well. Also keeps scopes from slipping on your hard-recoiling powder-burners.

Since moving to one-piece mounts, I've found lapping superfluous - the rings are 'perfect' from the factory; Leupold, Nightforce, even Monstrum ( inexpensive Chinese brand from Amazon). At this point, if rings need to be lapped, I consider them defective. 

GsT
 
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Great points made. I agree about lapping on the dedicated rail/Gun they're going to be used for. 
My contribution is use feeler gauges for equal spacing when tightening rings down, left/right, back/front, paired forever. 
As you tighten down, you have the feeler gauges to ensure everything is true. Yeah you might need 4 pairs but it's precise. 
 
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Great points made. I agree about lapping on the dedicated rail/Gun they're going to be used for. 
My contribution is use feeler gauges for equal spacing when tightening rings down, left/right, back/front, paired forever. 
As you tighten down, you have the feeler gauges to ensure everything is true. Yeah you might need 4 pairs but it's precise.
Click to expand...

Yes! Excellent point to make. I used a scrap piece of brass flat stock to gauge out the cap-to-base gap, with some eye-balling. It does look really off when cap sits off to one side, but otherwise a straight shooting scope.

Kinda my first HOW-TO for the AGN, please forgive the left out parts.

Thank you James!
 
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