Lapping "High end" scope rings?

[SDHNTR]

Lapping assumes a false premise. It presumes that either your action or rings are incorrectly machined from the factory, which just isn't the case 99% of the time. I've never seen a circumstance which requires rings to be lapped. It's just an extra way someone has found that departes you from your money

You haven’t seen many rifles then, or don’t know what to look for.

 

[SDHNTR]

That is what I do, bed the rail to the action using blue locktite. When that cures, tighten the mounting screws to the final torque. I made sure no locktite was attached to the screws during the bedding, but for the final torque I added locktite.

Loctite is not a bedding material. Its not viscous enough to be an effective liquid shim, nor does it dry hard enough.

 

[SDHNTR]

Sorry lad, you've been had by the industry. I've mounted Talley rings, Weaver, Burris, Leupold, and a few others in my time. Which was the best? None of them. They all mounted scopes for me, friends, and family members without fail. Watch this first then respond to me.

One of the worst videos I’ve ever seen on the subject. Wrong in so many ways. Fudd to the max. The most ironic element being that he’s mounting a scope with very obvious and significant ring pinch damage, resulting from the very circumstance he says doesn’t happen. Laughable.

 

[RockAndSage]

One of the worst videos I’ve ever seen on the subject. Wrong in so many ways. Fudd to the max. The most ironic element being that he’s mounting a scope with very obvious and significant ring pinch damage, resulting from the very circumstance he says doesn’t happen. Laughable.

I got partway through on that one and just stopped, it was so bad.

 

[TheHammer]

That is what I do, bed the rail to the action using blue locktite. When that cures, tighten the mounting screws to the final torque. I made sure no locktite was attached to the screws during the bedding, but for the final torque I added locktite.

Very similar process to what I do,
but I use a slow set epoxy, much like jb weld marine. Make sure whatever you are using it is solvent resistant. Once the rail is set I typically bed the ring bases. Then check alignment and trueness. If a lap pass or two is required then that is next, I use a tiny dab of the same epoxy at the bottom bases and set my scopes. Usually a very little bit of epoxy squeezes out, carefully remove excess. All fasteners receive purple loctite. Rings torques as recommended and double checked +2ftlbs over which typically do not move at all, due to the loctite being setup. Zero issues once this process has been implemented. And improved repetition In accuracy. All stocks epoxy bedded to each action as well.

 

[Bencheifin]

So my question is this.... if I just forgo the rings and buy a one piece mount does that solve the problem all together? What advantages do you get from rings that you won't get from just buying a one piece that's good to go?

 

[RockAndSage]

So my question is this.... if I just forgo the rings and buy a one piece mount does that solve the problem all together? What advantages do you get from rings that you won't get from just buying a one piece that's good to go?

A lot depends on the rifle, but the advantages of separate rings are they're lighter weight overall, and when mounted directly to the rifle's receiver they can be mounted much lower than with a rail, and especially compared to a rail and a one-piece system, typically.

So it depends on the gun and intended use. Building an ultralight mountain rifle? Go with lightweight 2 piece rings, but plan on all those different surfaces and fasteners needing extra attention for max reliability and precision. If you're not worried about weight, then you have a lot more options.

All that said, I still lap my 1-piece mounts, and they've all needed it to greater or lesser degrees - just nowhere near as much as separate rings. Honestly, with a couple it may be debatable whether the amount of truing that occurred would have caused problems for the mounting without it being done, but there's a great peace of mind that also comes with having done it. The kit is cheap and surprisingly quick and easy to use, and I think more people would use do it if they knew that, and the benefits that come from lapping.

 

[IdahoBeav]

Are high-end rings and rails machined with less accuracy than the lapping bar was? How about the accuracy of the machining on the scope tube? And then there is the malleability of the aluminum scope tube vs that of the steel rings. As for bedding the bases, how does the compound harden and expand so much that it is subjected to the same force as the areas of the rail and receiver that touch and pull tight? The screws on the rings are not going to tighten exactly the same on the lapping bar as they will when you mount the scope. Each time threads are tightened, the metal loses some of its strength properties.

Land surveyors have a term they use, "chasing dust". It may be applicable here.

 

[RockAndSage]

Are high-end rings and rails machined with less accuracy than the lapping bar was? How about the accuracy of the machining on the scope tube? And then there is the malleability of the aluminum scope tube vs that of the steel rings. As for bedding the bases, how does the compound harden and expand so much that it is subjected to the same force as the areas of the rail and base that touch and pull tight? The screws on the rings are not going to tighten exactly the same on the lapping bar as they will when you mount the scope. Each time threads are tightened, the metal loses some of its strength properties.

Land surveyors have a term they use, "chasing dust". It may be applicable here.

Yeah, no, it's not applicable - and the cheaper the parts, the more important it all is. All of this was explained above.

High end rings? They get out of true as soon as you torque them down. Especially on a receiver that didn't have the screw holes tapped absolutely perfectly, or onto a receiver that had just a slight bit of variance to perfection in its coatings, or its machining. Yes - even perfectly machined scope rings need lapping after they've been torqued down. Just not as much, in most cases, as cheap ones.

Lapping bar vs rings? You're truing them to each other.

Malleable aluminum scope tubes? This is one of the biggest, most important reasons to lap your rings - that malleability in unlapped rings translates to physical deformation of the tube, impingement on its internals, and a scope that will have reduced reliability, repeatability, or just difficulty in having its internals move with precision.

It all matters - and the higher the quality the components, the less it matters. But it still matters.

What Bubba does with his Tasco and hand-tightening is not jUsT As gOoD even if he's got Spuhr, Masterpiece Arms, or some other set of multi-hundred dollar rings, as it would be with lapping and properly calibrated torque and bedding. And the cheaper the scope, the greater the chance you stand of actually damaging it, permanently.

 

[wapitibob]

Machining round ring bores isn’t the problem. The problem is mounting two rings on an action and trying to maintain cylindricity between the ring bores.

 

[IdahoBeav]

Yeah, no, it's not applicable - and the cheaper the parts, the more important it all is. All of this was explained above.

High end rings? They get out of true as soon as you torque them down. Especially on a receiver that didn't have the screw holes tapped absolutely perfectly, or onto a receiver that had just a slight bit of variance to perfection in its coatings, or its machining. Yes - even perfectly machined scope rings need lapping after they've been torqued down. Just not as much, in most cases, as cheap ones.

Lapping bar vs rings? You're truing them to each other.

Malleable aluminum scope tubes? This is one of the biggest, most important reasons to lap your rings - that malleability in unlapped rings translates to physical deformation of the tube, impingement on its internals, and a scope that will have reduced reliability, repeatability, or just difficulty in having its internals move with precision.

It all matters - and the higher the quality the components, the less it matters. But it still matters.

What Bubba does with his Tasco and hand-tightening is not jUsT As gOoD even if he's got Spuhr, Masterpiece Arms, or some other set of multi-hundred dollar rings, as it would be with lapping and properly calibrated torque and bedding. And the cheaper the scope, the greater the chance you stand of actually damaging it, permanently.

I'm not talking about cheap parts and scopes. Cheap parts have a good chance of being machined at tolerances that aren't as tight as that of a $100 Chinese tool and the work of your hands. We're talking about high-end parts.

Once you torque the rings onto the scope tube, things are going to move a little, and then there are the effects of temperature. The rings and rail are under constant and slightly varying stresses. You can't get it all out even if your hands are as good as the top CNC mills.

Bubba and his Tasco probably should lap if he wants to eliminate the possibility of marring his scope with the torqued rings. I have not seen a scenario with a high-end rail, rings, and scope where the scope did not spin and slide freely without lapping in rings finger tightened on the scope and torqued at the base, and when the scope is removed after torqueing and there were indentations in the scope that were visible to the degree that there was damage.

The scopes also have a matte bead-blasted finish, which is not perfectly smooth. Do we need to sand down the scope tube?

 

[RockAndSage]

I'm not talking about cheap parts and scopes. Cheap parts have a good chance of being machined at tolerances that aren't as tight as that of a $100 Chinese tool and the work of your hands. We're talking about high-end parts.

Once you torque the rings onto the scope tube, things are going to move a little, and then there are the effects of temperature. The rings and rail are under constant and slightly varying stresses. You can't get it all out even if your hands are as good as the top CNC mills.

Bubba and his Tasco probably should lap if he wants to eliminate the possibility of marring his scope with the torqued rings. I have not seen a scenario with a high-end rail, rings, and scope where the scope did not spin and slide freely without lapping in rings finger tightened on the scope and torqued at the base, and when the scope is removed after torqueing and there were indentations in the scope that were visible to the degree that there was damage.

The scopes also have a matte bead-blasted finish, which is not perfectly smooth. Do we need to sand down the scope tube?

All of these "objections" you keep throwing out can be applied or ginned up for every single aspect of building a reliable, precision rifle - from load development to blueprinting an action to, yes, properly mounting a scope. Do you think the idea that you can find some distant point of pedantry invalidates all the rest of these practices?

You're being provided info that top builders do, and rejecting all of it because...what...you don't do it?

Have you ever even lapped a pair of mounted scope rings?

Regarding the bead-blasted scope finishes, yes, that bead blasting reduces surface-contact area, you're right - and it's part of why heavy-recoiling cartridges in lightweight guns often have their scopes slip on them. And it's why guys often overtorque the rings in response, and permanently damage their scopes.

Here's one of several solutions for that surface issue (which also includes wider rings, and wider rings with greater numbers of fasteners to distribute that proper torque and applied force more evenly): https://next.henkel-adhesives.com/u...tite-641/BP000000153498.html?variantId=231121

 

[wind gypsy]

I had a seekins havak in which the pic rail that came with it did not fit well to the action at all and it needed bedded to avoid it being bent by the base screws. You'd think an element with the integral (i think?) rail would be less likely to have issues.

I never lap rings anymore but maybe I should check some to see how uniform the contact is.. Enough clamping force to hold a scope in place is deforming the tube a little anyway but I cant argue with a more uniform clamping pressure being mo better.

 

[RockAndSage]

I had a seekins havak in which the pic rail that came with it did not fit well to the action at all and it needed bedded to avoid it being bent by the base screws. You'd think an element with the integral (i think?) rail would be less likely to have issues.

I never lap rings anymore but maybe I should check some to see how uniform the contact is.. Enough clamping force to hold a scope in place is deforming the tube a little anyway but I cant argue with a more uniform clamping pressure being mo better.

Totally agree, you would think it would be less likely to have issues. My experience with lapping/bedding during scope mounting since I was a kid, trying to fix problems and understand their root causes, is similar to what I've learned about scopes and drop-testing here on Rokslide: The more I learned, the more I realized how little I actually knew before - and just how wrong what "everybody knows" can be.

I didn't bother lapping until I damaged a scope by doing what I'd always, carefully done - and now that I lap every single mount, it's shocking how every single setup has needed it, to greater or lesser degree.

Same with my old Leupolds, and even a very, very nice couple of Swarovkis - "everything's fine" until you realize the hard way that there are, indeed, some scope brands that don't lose zero from a bad bump, or that will indeed track perfectly over and over and over. Unless you have that bump, or try to have it track consistently - unless you push gear beyond "everything's fine" - you have no idea you're at the edge of it's abilities, or that other brands/methods eliminate those problems.

It's like the guy who drives around on balding tires - "it's fine" is fine until circumstances change slightly.

I don't like it when I discover I've been unknowingly driving around on balding tires. Especially when they're expensive and supposedly of a better quality.

 

[IdahoBeav]

All of these "objections" you keep throwing out can be applied or ginned up for every single aspect of building a reliable, precision rifle - from load development to blueprinting an action to, yes, properly mounting a scope. Do you think the idea that you can find some distant point of pedantry invalidates all the rest of these practices?

You're being provided info that top builders do, and rejecting all of it because...what...you don't do it?

Have you ever even lapped a pair of mounted scope rings?

Regarding the bead-blasted scope finishes, yes, that bead blasting reduces surface-contact area, you're right - and it's part of why heavy-recoiling cartridges in lightweight guns often have their scopes slip on them. And it's why guys often overtorque the rings in response, and permanently damage their scopes.

Here's one of several solutions for that surface issue (which also includes wider rings, and wider rings with greater numbers of fasteners to distribute that proper torque and applied force more evenly): https://next.henkel-adhesives.com/u...tite-641/BP000000153498.html?variantId=231121

You're appealing to tradition and authority (which are logical fallacies) in much of your reasoning. I'm only asking questions involving imperfections and a doubt that the tools and technique involved with lapping are solving a problem that is left over in the production of a high end setup with a rail, rings, & scope. I'm also asking if a problem really exists in this situation.

I have lapped a pair of scope rings, but they were two piece bases, the Leupold style with the rear windage adjustment and the front twist lock. I believe the lapping helped, but this is a different configuration than a high-end rail, rings, scope.

As for torqueing, is it possible that torqueing to spec on a high-end rail setup remedies the miniscule issue that you are trying to address with the lapping?

 

[sndmn11]

When moving scopes between rails, how does one lap rings to compensate for all of the possible variations? If the concept is that rails aren't true and actions aren't true, are they all identically untrue or does lapping to correct for rifle A potentially make things worse for rifles b-z?

 

[RockAndSage]

When moving scopes between rails, how does one lap rings to compensate for all of the possible variations? If the concept is that rails aren't true and actions aren't true, are they all identically untrue or does lapping to correct for rifle A potentially make things worse for rifles b-z?

New rifle = new rings. They need to be trued in place. Leave the old rings on the original rifle, and they'll be good to go for whatever scope you eventually put back on it.

 

[RockAndSage]

You're appealing to tradition and authority (which are logical fallacies) in much of your reasoning. I'm only asking questions involving imperfections and a doubt that the tools and technique involved with lapping are solving a problem that is left over in the production of a high end setup with a rail, rings, & scope. I'm also asking if a problem really exists in this situation.

I have lapped a pair of scope rings, but they were two piece bases, the Leupold style with the rear windage adjustment and the front twist lock. I believe the lapping helped, but this is a different configuration than a high-end rail, rings, scope.

As for torqueing, is it possible that torqueing to spec on a high-end rail setup remedies the miniscule issue that you are trying to address with the lapping?

I'm doing no such thing - and in fact, it's this inane "i never lapped muh rings, never had no problems with it" mentality that is the appeal to tradition. Wrapped in the pedantry of trying to find some point of diminishing returns that, sure, way out there somewhere you'll encounter them. But that's also relative to your needs.

Buy your "deer gun's" ammo by the box? Measure your accuracy by "minute of pie plate" and never even notice a wandering zero? You're fine. Everything's fine. Don't worry about it.

But the more you value protecting your gear, and making it as reliable, repeatable, and precise as possible, the more each of these techniques and realities matters. If you don't understand the need from personal experience (or my failure and that of others to explain the need), then I guarantee you it's because you haven't pushed your gear hard enough or far enough to the edges of its capabilities to turn any of these problems up.

The only rail I trust not to bed? An integrally machined one. The difference between those who don't know this and those who do is the difference between those who buy their ammo by the case or by the box. I'm not trying to be elitist here - far from it. I'm trying to share hard-earned, very expensive and painful experience and knowledge, that makes a difference.

To your last question -

is it possible that torqueing to spec on a high-end rail setup remedies the miniscule issue that you are trying to address with the lapping?

Yes. It's part luck with the specific precision of the base and rifle, part quality of the rings. The stouter it is, as a 1-piece unit, the less likely you'll need to lap it, but there's almost always some degree of imperfection that shows up on lapping. But it only takes about 15 mins to lap rings. Would you not take 15 minutes to check the air in your tires before a long trip, or hauling a load? It's a 1 time thing.

The "miniscule" issue you will find even in high end rings matters more and more the thinner your scope tube walls are. It wouldn't likely be a problem at all for an old steel-walled scope. But a thin, lightweight scope? Yes, that little bit of variance will mess with the precision of that tube's alignment, and possibly its internals. A more robust, reliable scope? It matters less.

But all these luck and quality factors go way, way down in their impact and importance, just by lapping the damn rings. It takes 15 minutes.

That 15 minutes can save hours of chasing ghosts at the range and workbench trying to figure out why your gun won't group consistently.

 

[sndmn11]

New rifle = new rings. They need to be trued in place. Leave the old rings on the original rifle, and they'll be good to go for whatever scope you eventually put back on it.

That doesn't answer the question. You are truing for a specific rifle, correct? How does that impact things for when you move the scope and rings together to a different rifle?

 

[E.Shell]

Are high-end rings and rails machined with less accuracy than the lapping bar was?

As pointed out by other posters, the rings themselves, and degree of their precision, is not usually the reason to lap. The reason is the composite error of all mounting parts combined/added and their effect on ring axis alignment.

Rings of lesser precision also benefit from lapping by having sharp edges and high spots corrected.

One thing you will notice as a recurring pattern when lapping is that while the rings are machined, the thinner areas at the sides tend to deflect away from the cutter. After the cutter is retracted, that area of the rings spring back. Anyone familiar with metal machining has seen this deflection. Sharper tools deflect less, but some deflection is almost always evident. When the rings are lapped, this area is corrected and no longer grabs the scope as the scope tube enters the rings.

Lapping bars are merely round rod stock that slides between the loosely clamped rings. The diameter of the lapping bar is typically a few thousandths of an inch less that the corresponding scope tube diameter, in order that we do not loosen the fit if done properly..

We are only ensuring alignment of the ring axes, not re-cutting the bores.

How about the accuracy of the machining on the scope tube? And then there is the malleability of the aluminum scope tube vs that of the steel rings.

This is all about being kind to the scope. The scope tube, unless junk or damaged, can be assumed to be straight and cylindrical and we are using the lapping method to ensure it lies in alignment to the ring bores.

As for bedding the bases, how does the compound harden and expand so much that it is subjected to the same force as the areas of the rail and receiver that touch and pull tight?

When bedding bases, the standard practice is to lightly tighten the base screws just enough to press the base down onto the bedding compound, not squeeze the material out. Once the compound is cured, the screws are brought up to the specified torque value and nothing moves during that process.

Epoxy expansion does not affect this process, nor contribute to tightening the screws. Bedding the base normally helps with keeping the ring bores aligned and reduces the need to lap, but there are often sharp edges and/or high spots and lapping will address these.

The screws on the rings are not going to tighten exactly the same on the lapping bar as they will when you mount the scope.

This may be the source of your questions...the ring screws are NOT tightened down onto the lapping bar with any substantial force and certainly not clamped onto the bar or brought up to torque.

When I was teaching long range precision, I usually helped students with installing their scopes. Most people really don't know how to properly mount a scope and I usually saw both eye relief errors and almost always out of level. I used a Starrett 4" machinist's level to correctly level long range scopes.

I have mounted several hundred tactical/precision scopes in the following manner:

Picatinny style mounts:
The rings are set loosely onto the base, pressed forward against the face of the slot and the clamp screws lightly tightened.
The lapping bar laid onto the bottom ring halves and first used as an alignment tool.
The ring caps are lightly snugged up on the bar to align them to each other as closely as possible.
The ring clamp screws are then torqued to the base. You will not touch these clamp screws again.
The ring caps are removed.
The lapping bar is removed, loaded with lapping compound and set back into the bottom ring halves, now to be used as a lapping tool.
The ring caps are placed back on and the cap screws lightly snugged.
The bar is then slid back and forth inside the rings, using a push/pull motion with light rotation.
As the compound is exhausted and the rough/high spots worn down, chase the bar down by lightly tightening down the cap screws. At no time during lapping will the ring screws be "tight".
You will be able to feel when the lapping compound is completely exhausted and stops cutting, and you will stop at that time. One cycle is usually enough to take care of the worse of it.

Remove and clean the ring caps and lapping bar. Keep the respective ring cap both matched to the ring bottom and oriented the same. I usually index mine and students with a very small prick punch where the rings meet - one dot at the front, two dots at the back.
Clean the ring bottoms.
Inspect the condition of the ring contact surfaces. You will be able to see finish wear where material was removed. I usually go for about 50-75% contact. I do not completely remove the interior finish. Note at this time that the areas touched by the lapping bar were the high spots and pressure points against your expensive scope tube.

Once you have 50% or so contact, make sure everything is clean, loosely install the scope and ring caps, level your scope, set your eye relief and torque your ring cap screws.

Each time threads are tightened, the metal loses some of its strength properties.

Torque values are designed to deform (stretch) the screw just enough that it will return to its original shape when pressure is released. You are correct and yes, this DOES weaken the screws more and more each time, ** IF** we actually torqued them down onto the lapping bar, which we DO NOT.

Land surveyors have a term they use, "chasing dust". It may be applicable here.

If you would:
a) like to have your scope work as smoothly (magnification and parallax adjustments) as designed, and
b) like to have the best stability via increased/improved tube/ring contact, and
c) wish to eventually resell your scope without ring damage ("ring marks"), then
it's NOT "chasing dust" and *proper* lapping is a good idea.

If one doesn't care about any of that, one shouldn't bother with lapping, but also shouldn't object to those that do.

Machining round ring bores isn’t the problem. The problem is mounting two rings on an action and trying to maintain cylindricity between the ring bores.

^^^ This ^^^ ....mostly. In most cases, we will still see a slight out-of-round condition due to cutter deflection.

When moving scopes between rails, how does one lap rings to compensate for all of the possible variations? If the concept is that rails aren't true and actions aren't true, are they all identically untrue or does lapping to correct for rifle A potentially make things worse for rifles b-z?

Look at this process as matching the rings to a particular rifle/base platform.

As already pointed out, one would leave the rings with the rifle and simply swap scopes without disturbing the bottom halves of the rings.

You are correct to think that lapping rings into alignment on one rifle might make the misalignment worse on another gun.