Lapping rings, worth the $?

[13JFO]

Got ahold of a Mosin PU with a great bore and sharp rifling. I want to play around with how far out I can take this thing. Putting a modern scope on it, but got into a discussions with someone at the range about lapping scope rings.

Is it worth the cost? These lapping kits go for a pretty penny.

[DougGuy]

That's a rather subjective question. On one hand, modern rings are pretty well made and it also depends on the type of ring. Otoh, if you do buy a lapping kit and your rings start showing lap patterns that are indicative of poor alignment, then yes that is a variable you would have likely not found and probably fought it until you addressed it.

What I do is buy a precision ground pin from McMaster Carr that is 30mm or 1" and I use that to snug the rings onto while tightening the bases, and I often bed the bases when I can. This more or less eliminates the need for lapping.

[Mk42gunner]

I tend to agree with DougGuy on this, in that it depends. If your base and rings are straight and line up right, I don't think it is really needed. But if the rings are misaligned even a degree or two, lapping can help prevent those nasty ring marks on scopes or even bending the scope in extreme cases.

Look at it like this-- it is a one time expense, and then you have it if you ever want to lap or just check the alignment.

Robert

[rancher1913]

the things you learn on this site that you never knew you needed to know

[Jedman]

I was given a ring lapping tool and tried it once the way you are supposed to use it and found it would take a month of lapping by hand to get anywhere.
I chucked mine in the lathe and drilled and tapped the end of the 1” bar and can now use a cut off bolt chucked in a cordless drill to spin it while moving back and forth.
You would be surprised how little contact area most rings have. A lot of my rifles have aluminum rings so I wouldn’t use lapping compound on them , I have only done a few pair of steel rings so far.

Jedman

[Traffer]

From what I have heard...it's BS ...forget it.

[30calflash]

Instead of purchasing a lapping kit I got a piece of 1" stock from Brownells. It was about 10" long and with some valve lapping compound worked fine. It also went very quickly, like a few minutes. The rings were not off much to be truthful.

[Minerat]

I have these on my 300 wby and 7 mm rem mag. They have not slipped and stay zeroed https://www.burrisoptics.com/signature-rings

I use finger nail polish as loctite on bases and rings. Weatherby has been setup this way for 10 years and gets about 50 full power rounds a year thru it. Might be an option.

[country gent]

Make you lapp from bar stock. Brass or steel can be ordered from online metals. 12: length and a 1/4" x 20 bolt 3-4" long for the handle. These can be ordered from online metals fairly reasonable, shipping costs can be an issue though.

As you work the lapp add a few drops of oil. working the lapp in a figure 8 pattern.Work the lower halves in while mounted to the rifle to around 60-70% clean up then add the uppers in.

I use a coarser grit around 220-280 the coarser finish hold resin better. Remember as you work the compound breaks down and dulls cutting finer.

Aluminum anodized rings the anodized finish can be as hard as 70 rc so it may cut hard and slow.

Dont forget to break the sharp edges raised also.

[megasupermagnum]

Use Warne rings. They are the only rings I use anymore. The split design self aligns, I've never had one leave a ring on a scope.

[Cap'n Morgan]

Lapping scope rings is a solution to a (mostly) non-existent problem. DoughGuy's suggestion is much better. If you bed the bases with Lock-tite and don't tight them fully down before it has cured, the rings will match perfectly. I'd used this system on quite a few rifles where I made custom mounts, skipping the bases completely and mounting the lower ring directly on the action.

I like Sako's mount system which incorporates a split plastic inlay between scope and rings. The inside of the rings and outside of the inlay are matching spheres, guaranteeing perfect alignment, and the soft inlays give a good grip while not marring the scope.

[Ed K]

There are plenty of scarred up scopes to prove what the majority are doing is insufficient.

[B R Shooter]

Lapping scope rings is a solution to a (mostly) non-existent problem. DoughGuy's suggestion is much better. If you bed the bases with Lock-tite and don't tight them fully down before it has cured, the rings will match perfectly. I'd used this system on quite a few rifles where I made custom mounts, skipping the bases completely and mounting the lower ring directly on the action.

I like Sako's mount system which incorporates a split plastic inlay between scope and rings. The inside of the rings and outside of the inlay are matching spheres, guaranteeing perfect alignment, and the soft inlays give a good grip while not marring the scope.

Between these rings (which I was unaware of) and Burris Signature rings, are the only rings that don't need to be lapped. On production guns (new, old, military) there is no guarantee the action surfaces are at the height they are supposed to, the mounting holes are drilled properly OR in alignment with one another. The ONLY way to know this is by lapping. Let me also add, there is no guarantee rings are bored in alignment with the machining from which they mount. The ONLY way to know this is by lapping. Lapping will not cure mounts/rings/actions that are not in alignment. These rings with inserts can solve that problem easily with a little patience, with the offset inserts, can usually be cured.

Scope are more accurate when their adjustment is in the middle of their adjustment. When the erector tube gets to the extreme travel, they just don't move as accurately. Scopes are very expensive nowadays, or some are. I cringe at the thought of putting a $1000 to $2000 scope in a set of rings that are not lapped and proper.

This has been discussed and argued just as often and with as much passion as how to chamber a barrel.

[Bazoo]

Is there any benefit to lapping the old weaver rings?

[B R Shooter]

I have found the old wrap-around rings weren't so much of a problem themselves (assuming they are in alignment) it was the bases that had "knobs" that were higher than the rest, and made dimples in the scopes.

[Bazoo]

I don't follow BRshooter, could you elaborate a bit? Thanks.

[RedlegEd]

Hi all,
Love the discussion going on here. I agree with DougGuy to a point. The foundation is making sure the bases are mounted well. However, as been pointed out, not everything lines up as it should, especially with two piece mounts. I bought the Kokopelli Accurizing Kit to make sure that the bases and rings were in the best alignment they could be. Lapping is only a last solution when you need to tweak in that final little bit of alignment. It may not be worth the expense if you only need to do one scope, but I've scoped at least a dozen of my rifles with this and wouldn't give it up for anything.
Ed

[B R Shooter]

I don't follow BRshooter, could you elaborate a bit? Thanks.

It's been a long time since this happened. I bought an XP100 that had them on it, but no scope. I had a brand new Weaver KT15, put it on and tightened the rings down, the scope wouldn't adjust. Took it of and there were two dimples in the side of the scope that so happened to be were the erector tube pivoted. The base of the ring set where the two screws attached in the downward position, the casting had bumps I assume to beef up where the screws attached. Weaver replaced the scope, I replaced the rings.

[nicholst55]

That piece of cold-rolled 1" (or 30mm) stock you bought to make a poor-boy lapping kit typically isn't a true 1" (or 30mm) diameter. Measure it before you start lapping away. It is typically oversized by several thousandths of an inch.

[smithnframe]

I wouldn't waste any money lapping scope rings for a M-N unless it was owned by the Czar himself!