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Discussion Starter #1
Part 1.

Why should scope rings be lapped, aligned and torqued?

Even a cheap scope is a precision optical device, so it needs to mounted straight (aligned), with rings and bases torqued correctly (so as to not crush the tube and put pressure on the lenses). Variable scopes, and higher power scopes are most susceptible to distortion caused by improperly aligned/lapped/torqued rings. Second Focal Plane variable scopes (American style where the crosshairs remain a constant size) are prone to suffer from a "shifting zero" as the power is changed, but much of that is due to lack of lapping/alignment. Low powered variables, and fixed power scopes are not as "twitchy", but their rings should still be lapped, aligned and torqued.

There are several variable surface dimensions involved when mounting a scope straight.

1.) The action. As actions are machined during manufacture the cutting tools get duller with every action made. Surface imperfections and variances from one to the next. Final polishing of the metal does more to change the final specs.

2.) Bases. The same machining process as above leaves each base with it's own variable tolerances.

3.) Rings. Rings are machined the same way, and have their own variances.

When all these variable surfaces are combined, it adds up to a set of rings that are almost always out of alignment to some degree once they are mated to a scope.

The quality/expense of the rifle/base/rings used does not matter. The worst set of rings I've ever seen were a set from a high end manufacturer, and the cost was almost $300. They were visibly off right out of the package by over a millimeter.

For the shooter who does not want to spend the money on the right tools to do this job, get your friends to pitch in. Then you can all help each other do your rifles. Every time I'm at the range with my tools, someone asks me to lapp their rings. They always try to pay me, so investing in the tools could end up a money making venture for most shooters. When I did this stuff for a living the going rate to lapp, torque and mount was $75-$150 depending on the amount of work needed. It can pay for your tools quickly.

But what if you check the alignment of the rings and they are perfectly straight? It is rare, but does happen. Well, the rings may be straight, but the bearing surfaces of the rings will have high spots and ridges. These need to be lapped away so the ring surface is smooth and fits flat against the tube of the scope. Any high spots on the inside of the ring surface can cause dents and pressure to the scope tube when the rings are tightened down.

My old FN Mauser in 7x57 needed to be lapped, so she is the model I used in this post.



Tools needed were:

Brownells screw driver kit (the best kit I've ever used)
Wheeler FAT Wrench torque wrench (not the most accurate on the market, but consistent and accurate enough when a 5 inch pound +/- is good enough)
Kokopelli Products accurizing kit (The best on the market, by far IMO)
Two small Stanley bubble levels
Q-Tips
Paper towels
Tipton rifle cradle
Acetone





I prefer one piece Picatinny or Weaver bases because they are designed to align themselves fairly well, and can be mounted and remounted with almost no loss in POI (Point Of Impact). But in this case I chose a rifle with a one piece Redfield/Leupold style base, which is very common. These are called "windage adjustable bases". The windage adjustment is in the large knobs on the sides of the rear ring. But the front ring fits very tightly into the base, so using the rear windage screws for adjustment purposes will bend the scope tube left or right, which leads to an "oval-ing" of the image through the scope. Don't use them for adjusting impact with the scope tube installed, and only for gross adjustments while setting up. Fine adjustments are done with the knobs on the scope.

Continued on next post...
 

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Discussion Starter #2
Part 2.

Getting started.

Clean all the screws and screw holes with acetone (action, bases, rings, cross bolts, etc),

Torque the base screws down to about 30 inch lbs. For Weaver and Picatinny rings, torque the clamp screws or cross bolts to about 30-35 inch lbs. Once the ring bottoms are mounted to the base, check to make sure they are aligned, or close to being aligned (the Kokopelli front alignment bar has a hole in the end, and a rod that goes into the hole so that you can see how it lines up with the bbl.


The flat ends of the two alignment bars should line up (flat ends touching), edge to edge and be relatively straight. If more than a fingernail's width of overlap is evident, switch the rings around, turn them around, etc.



Find the position that aligns them best. Torque the rings down and get the lapping bar ready. The Kokopelli lapping bar has a groove machined into its surface to allow the lapping compound to stay in place during the lapping process.




The cheaper alignment bars with the pointy ends are terrible because points can line up, even if the rings are not aligned. Flat ends only line up when the rings are perfectly straight.

When you are finished with the lapping, the ring tops will be mated to the ring they are attached to, in the direction they are mounted, permanently. Mark the ring tops (front and rear), with an arrow pointing forward, using white out or a crayon, etc. I used black Sharpie marker, this time, because it was handy. "F" for front ring, "R" for rear, with an arrow pointing forward. This cleans off when you finish, leaving no permanent marks. If you ever need to remove the ring tops, mark them before you do so.
 

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Discussion Starter #3
Part 3.

The actual lapping process is pretty straightforward.

Coat the lapping bar with a thin film of lapping compound, set it in the ring bottoms, and place the ring tops on. Put the screws in place and lightly tighten the screws (only til you feel resistance). I use the screwdriver bit between my thumb and forefinger to avoid over doing it. Once the rings are snug start working the lapping bar from side to side to take off the first edges.



At first there will be a decent amount of resistance. As moving the bar becomes easier, keep moving the from bar side to side and add in a front and back motion too; Almost a screwing motion. After 10-15 reps you will notice the bar moving easier due to material being removed from the rings. Lightly tighten the screws again until you feel resistance. If using rings with 4 or 6 screws tighten them in a cross pattern. It may only take 1/6th of a rotation on each screw, or less. Not very much. Do this a few times, keeping an eye on the gap between the top and bottom of the ring (where the screws go through) to make sure you don't remove too much material. You only need about 80% to 85% bearing surface on the ring surface.

After you have done 3-6 (or so) series of 10-15 reps, your rings should be ready to check.

Remove the lapping bar and wipe the rings clean with a rag. The lapping compound stains, so be careful. If you remove the ring tops to get the bar out, remember to pay attention to which is front/rear and which direction is pointing forward. Those rings are now mated in the place you set them originally.

The inside of the rings should now be a matte silver, and have a smooth feel with no ridges.

BEFORE.

AFTER.


80%-85% of the surface is all that is needed to be flat and smooth for a good fit. If your rings look like that, you are good to go. Clean them up with acetone and use the Q-Tips to clean the screw holes. Get the threads on the screws and holes clean.

When you set your scope into the ring bottoms after lapping, it should freely slide forward and back with no "scraping" feel.
 

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Discussion Starter #4
Part 4.

Adjust your scope for your eye relief (if you have questions about this please ask), and make sure the crosshairs are straight up and down. There is almost always a flat part across the action somewhere to use for this. The other flat part is the top of the adjustment knob, or cap.



It is easiest done if you have a clamping rest like the Tipton.


Then, tighten the ring top screws in a criss/cross pattern. Pay attention to the bubble levels as you tighten the screws as that will twist the scope out of the perpendicular.

Proper torque for aluminum rings is 10-15 inch lbs, while steel is 15-20 inch lbs.

It is a very simple process, but one that pays huge dividends.



 

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Discussion Starter #5
Part 5.

How the alignment bars SHOULD line up before lapping. The knife tip is at the junction of the ends. These are close, but not perfect, but will be by the time we are finished.


Using the two levels to verify level spots. Notice the clean, post lapping ring surfaces.


A better shot of the steel rod used to align the rings with the centerline of the barrel.


A better shot of the "Pre-Lapped" rings showing the high spots and ridges. Very noticeable.
 
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Part 6.

So before you guys jump all over me, I know the rifle pictured here is NOT an M14. DI2 But the same variables apply with M14 mounts/rings.
 
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Thank you very much for posting this, it is incredibly informative. You did an excellent job explaining all this. I had a vague idea what it entailed, but not nearly to the extent you displayed. It was all very clear to a newbie. I sincerely appreciate your time.
 

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Thank you very much for posting this, it is incredibly informative. You did an excellent job explaining all this. I had a vague idea what it entailed, but not nearly to the extent you displayed. It was all very clear to a newbie. I sincerely appreciate your time.
My pleas. Thanks for the kind words.
 

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Good job on the presentation, and showing how all the tools are used. It's also good your showing how levels are used and why.
 

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Overall a pretty good article. You covered the basics in detail.

Another type of ring that is a great asset while using windage adjustable bases and no need to lap them is the Burris Signature rings with the plastic inserts. These work quite well in most applications. The plastic inserts are also used to center the scope in large adjustments to the rifle. The inserts are offset. It takes a little longer to zero a scope with these but once it is zeroed, you still have most of the adjustment left in the scope. They work like a ball joint and do not stress the scope as the inserts are allowed to pivot with the scope. And will not allow the scope tube to be crushed or bent. Also, I would recommend torquing to the ring and base manufacturers specifications, and also using the proper loc-tite. As far as the lower power scopes go, the lower the capable magnification, the more adjustment a scope has. The larger the outer tube, typically the more adjustment a scope has. Shifting zero when the magnification is changed is due to the reticle not being centered in the guide tube. Shifting zero after each shot is more likely the cause of the mounts or rings being loose, or the scope is under stress while clamped in the rings. And in some cases there is something wrong with the scope itself. A bent scope caused by the rings or the scope being dropped or hit will have drastic effects on the scopes zero and its ability to be zeroed. This is meant to be constructive as there are several products out there and it can be quite confusing.
 

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Discussion Starter #13
The Burris rings work the same way the old HK ring inserts worked. Fine for some. Still possible to over torque, though, so be careful.

Most recreational shooters will never know the difference, but once the skill level goes beyond "recreational" the need for high quality rings and lapping becomes evident.

My problem with Burris is their terrible customer service reputation, and spotty scope quality. Too many "Friday afternoon" products made it out the door.
 

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I disagree with you on Burris quality. They are my employer and I believe thay put out a good product. Like I said, your statements do hold a lot of truth when it comes to mounting scopes. There are just too many variables when it comes to point of impact issues and properly mounting a scope.
 

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Discussion Starter #15
I disagree with you on Burris quality. They are my employer and I believe thay put out a good product. Like I said, your statements do hold a lot of truth when it comes to mounting scopes. There are just too many variables when it comes to point of impact issues and properly mounting a scope.
Yes, I know you work for Burris. My thoughts on Burris are in your PM's.

The variables you mention are precisely why rings need to be lapped.

On any rifle, once the base/mount is mounted to the receiver and torqued correctly, the rings are moved around until the best alignment is found. The Kokopelli accurizing bar has a provision for visually assessing alignment, as was shown in the OP.

Assuming that high quality equipment has been used the alignment will be within acceptable specs. Then the rings can be lapped for virtually perfect alignment.

If the rifle used is an old milsurp that has been poorly sporterized the specs can be way off. When that happens, the receiver may need to be trued, or the mounts may need to be shimmed or fitted to gain acceptable alignment. These rifles rarely fall into the "precision" category, however.

In this instance the Burris offset inserts can be a very useful (and extremely cost effective) substitute for expensive gunsmithing.
 

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Thanks for the tutorial, M14srock. A lot of people do not realize that manufacturing processes will create a lot of variable tolerances that need to be corrected when they are assembled together as a unit. Most do not realize that it takes only 10 in/lbs to tighten the rings. I go thru the same process that you use when mounting my scopes/optics. If it's going to be done, it might as well be done right. dozier
 

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Thanks for the tutorial, M14srock. A lot of people do not realize that manufacturing processes will create a lot of variable tolerances that need to be corrected when they are assembled together as a unit. Most do not realize that it takes only 10 in/lbs to tighten the rings. I go thru the same process that you use when mounting my scopes/optics. If it's going to be done, it might as well be done right. dozier
Yep, too many variables. And when a ring manufacturer tells a customer "You do not need to lapp our rings" it is amazing. Even if the rings left the assembly line perfectly matched, there is no way to know the dimension of the mount/base they will be attached to, or the receiver.

Lapp them all.
 

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Discussion Starter #20
This is great stuff!!! I'm going to buy the accurizing kit. Got about a dozen rifles to do, great winter project.
Cool beans. John at Kokopelli makes some great stuff. Very interesting guy.
 
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