• Kokopelli Scope Ring Accurizing/Lapping Kit

    A while back the topic of 35mm lapping bars, and sources for the same were being discussed. Mr. John Werre of Kokopelli Products and I became engaged in a conversation regarding his Accurizing Kit and the need for it versus just getting a steel or brass 35mm bar, lapping the rings and calling it good.

    Quite frankly, I didn't think I needed an entire kit and thought that it was overkill. After some emailing back and forth, Mr. Werre offered to provide us a kit to try and evaluate for the site. I choose a 35mm kit as most of the staff have a 35mm scope. As the timing worked out I was the fortunate one to test the kit. My choice of words will become clear as you read on.

    The Hardware

    The kit arrived packed in a fitted case with the 35mm lap, removable handle for the lap, two precision scope bars, lapping compound, a drill rod to use for bore alignment and detailed illustrated instructions. The idea is to use the scope bars to verify the axial alignment of the rings, the drill rod slides in the forward scope bar to assist in aligning the mount and rings to the bore.

    Putting the kit to use

    When I got the kit I sat down, read the instructions and followed them step by step. The timing was good as I had just received my new IOR 3-18x42 Flea Scope and was ready to mount it and go.

    As I already had the base installed and rings mounted, I went ahead and placed the scope bars in the rings to see where I was. This was enlightening. As you can see I had a serious vertical misalignment between my front and rear rings. As close as I could measure the offset, it was just shy of .040. After regaining my composure, running through my saltier vocabulary, and calming down a bit I started investigating for the cause of the misalignment.

    I removed the rings and base and checked them for straight and true on a granite table. All the components were correctly dimensioned, and verified to be straight and true. Just to make sure, I took them to one of my customers Quality Control Labs and had them verify the same with their laser inspection and dimensioning system. They had the same results and were actually quite impressed with the tolerances of the TPS system (that is a different article though).

    At this point I went back to the rifle and began checking it. By trial and error, I found that with the base installed and tightened down with just the rear screws, all was still straight. However, when I tightened the front two screws of the base down, the forward bar canted down at the junction of the scope bars.

    The culprit was my receiver. After doing some research, I have found that this is not uncommon for rifle receivers. The receivers are heat treated after the machining process, and it is not so much a question of Is mine warped? as it is How much is it warped? I must admit, this was something I had not stopped to consider before this test. I knew I did not want to lap that large of a cant into my rings. They would be useless after that for any other rifle should I decide to switch scopes. Not acceptable in my opinion.

    But, since I knew where the problem was, it was a fairly simple and straight forward fix. I mixed up some Devcon Steel Bed and bedded the base while only securing the screws in the rear and using electrical tape to maintain the front of the base in place with the scope bars mounted in the rings to verify proper alignment. After it cured, I tightened it all down and here is the result.

    As the photos show, the alignment is now nearly perfect. After the Devcon had set, I colored the inside of the rings, and just ran the lapping bar a couple of times back and forth to see. I had outstanding surface contact, without having to remove any material at all.

    Conclusion and Summary

    I have to say, this has given me a whole new outlook on the whole scope mounting process and what is overkill and what isn't. While just lapping a set of rings with a bar to get good contact will in fact work, it does then commit those rings to that base and rifle. If you change scope sizes and go to a different set of rings, you have to do it all over and now you have two dedicated sets of rings for that rifle.

    It also defeats the purpose of the picatinny system in my mind. If I were to take that lapped set of rings and scope off of that rifle, and move it to my .300 wm and torque it down on that base, how do I know that Im not now bending my scope the other way and putting it in a bind? I may not see the ring marks in the lapped rings, but am I taking a chance that I am messing up an expensive optic? Its a danged good possibility based on what I learned doing this test.

    In my opinion, fixing the base to receiver alignment first is a much better long term option than just lapping rings. Then I know it is square and true and it gives me the option to move scopes from rifle to rifle as I choose to without worrying about ruining an expensive optic. Is that not the whole concept of repeatable and standardized rails and rings and why we pay big money for them in the first place?

    Im buying this one from Kokopelli Products, and I see the 1 and a 30mm kits finding a home my tool box very soon. Are they more expensive than just a lapping bar? Yes, yes they are. Are they worth it? Yes, yes they are. Given the cost of our optics, bases and rings, the piece of mind alone is well worth it.

    Additional Photos:

    Shot of the author's ring misalignment prior to bedding the scope base. Bedding the scope base
    Ring alignment after bedding

    Kokopelli Products

    3820 Foothill Rd.
    Kalispell, MT 59901
    Phone: (406) 755-3220