Home Forums Hunting & Shooting Hunting Rifles Kimber Montana inexplicable accuracy change

Shoot more groups...need moar DATA

New set of Talleys, unlapped, old scope back in place.
Should be GTG.

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Seems like many oppose lapping the Talley rings. What’s wrong with lapping them? What does it hurt?

I've always had best results without cleaning during a session. Ive also had some rifles that wouldn't settle down after cleaning until I'd put about a dozen rounds downrange.

I’ve never lapped a set of rings in my life and haven’t had an issue.

I would start over again from the beginning and see what you come up with.

What did it help?

If also agree on trying a new set of unlapped talleys. Lapping may not have hurt a thing but Talley specifically says not to.
I personally think with aluminum rings lapping causes more trouble than it fixes

I've lapped every set I've put on. No problems. I'm not marking up an expensive scope in a fifty dollar set of rings. If I ever find out it does cause a problem,I'm done with Talley. I've worked within the tool,die,and machine industry for going on 40 years. IF Talley can,and they can't, produce perfectly matched sets of rings,the holes in rifle actions are far from perfect. A few swipes with the lapping bar will tell you where you're at. If things are horribly crooked,you might just as well look to other mounting options. Burris sings with inserts come to mind. If things are great. Hitting both rings equally. Sally forth to enjoy lots of wallet groups and high fives.

Just curious. After flipping the front ring,how far off of "lapped" was it?

You do want to be careful not to impregnate the aluminum with compound. Lapping will remove the finish. That in itself is likely prompting Talley to promote no lap installation. I still don't agree totally. See above post for the reasoning.

+1, and don't clean the bore while you're shooting. Others have said it but you changed up so many things at once that this was far from inexplicable. It's just unexplained because you've introduced so many variables.

Put some rubber cement on your rings before you set the scope in place and you will never mark scopes again provided you dont farmer tighten the screws.

ahh kimber roulette

I don't understand this "neverlap a Talley" mindset. When I ordered my Hill Country Rifles 7mm Rem Mag they used Talleys, lapped them, and told me they lapped most every set of Talley's they install. They do know a thing or two about accuracy and how to set up a rifle.

So otter, you would have flipped the rings and lapped a second time as well? Who knows how much material the op removed in the process?

That was my thought as well. The way Otter is talking about lapping is the proper way to go about it. If everything is right then the aluminum rings won't need but a few passes to make everything perfect. If they are off bad,then another solution is necessary. Lapping isn't the problem. The judgement of the one doing the lapping is usually the problem.

Very Good Point . If he is done with Talley then he never ever needs to look at DNZ

Yes! I have done just that on a couple 6ppc bench rifles.

Lets not get carried away boys. I was just curious how far off it was in regard to the holes in the action. I'm not done with Talley yet. If I ever have the trouble a lot of folks predict I will. Ill drop them like a hot rivet. No, I buy them. Lap them. Go about my business.

As far as lapping the ring a second time. I doubt it. Personally, I dont get too carried away with the whole process. Taking a minimal amount of material . Can't say what the op did.

That's a good point. Never bought a DNZ mount. Too many opportunities for error. If they go so far as to wire EDM them,there is no guarantee they won't be off some small amount. All material has some come and go in it. Now assuming it did in fact stay put after being machined,there are the mounting holes. Are they exactly along the axis of the scope? Maybe. Maybe not. Ok, now we have perfectly machined aluminum one piece mounting hardware. If the holes in the action aren't perfect,we have no means of correcting it. Via lapping. Here is another little potential pisser. The rear bridge on Remingtons are rarely the exact height they are supposed to be. Now what? Shim the DNZ or just crank the screws down and hope the ring portion is still lined up. Ill pass.

Thanks for all the replies. I had no idea that lapping scope rings could be so controversial. Otter6 and a few others have made some interesting points, otherwise I am seeing only heartfelt opinions with no evidence or logical reasoning for opposing lapping. Talley saying not to do it is an unsupported assertion, which, by itself, has no supporting reasoning, and thus falls to Hitchen's Razor ("What can be asserted without evidence can be dismissed without evidence").

IMHO, the benefits of lapping are 1) no ring marks on the scope; 2) the larger contact area spreads the clamping force over a larger area; and 3) ensures the axis of the bores of each ring are co-liner with one another. The first point is undeniable and affects aesthetics and resale value, which by itself is sufficient justification for me. The latter two points reduce the stress on the scope tube and its internal mechanism, which may be overkill, but until someone provides evidence that it causes problems, is an option with no downside. Obviously there are other ways to achieve the same goals, such as the Burris Signature Zee Rings. JMHO and YMMV.

For the second lapping procedure, I applied black Sharpie Pen to the interior surfaces of the rings' bores, ie. the bare aluminum was blackened. I then lapped until most of that black ink had been removed and the entire surface showed scoring from the abrasive, which did not take long. I estimate on the order of a couple of thousands of an inch, at most, was removed from the rings' bores' surfaces. After lapping, the scope tube was placed in the lower mount body and checked for play. The scope tube was a snug fit into the mount without the upper ring in place.

Below is a closeup of the right side of the front ring of the subject rifle. The gap between the top ring and the mount body is about 0.025" by my micrometer. This gap distance is similar for both sides of both the front and back Talley mounts. This gap shows that, despite being lapped twice, the top ring is still applying a clamping force to the scope tube onto the mount. Thus, a snug pre-fit and plenty of clamping force means the second lapping had no ill affects on the Talley mounts' ability to properly hold the scope in place.





For the next trip to the range, I will go back to the Kahles scope, and mount it in Burris Signature Zee Rings with the nylon inserts, held in place with Warne Two-Piece bases. Thus, the whole scope-lapping controversy will be by-passed. When and if that first 1/2" group proves to not be a statistical anomaly, I will then retry the Zeiss Conquest scope in the same mounting system. If all goes well, I will then retry the lapped Talleys. During that process, I will shoot more groups, and change only one parameter at time, so I will know the cause if a problem develops.

Again, JMHO and YMMV