Flipping them around got them much closer with the alignment bars than the last pic, though I’m not sure I could set up the ER on my new scope with the rear ring turned around (don’t have the scope in my hands yet). After more testing after I took these pics I believe the front ring is level and the rear is the one that is off; I can turn the rear around and reverse the problem, seems to be a dead giveaway. I can’t swap the rings front to rear though. I also could not get the OEM scope bases to cowitness using the same level, so makes me wonder if it isn’t the Talley’s? Although they were much closer, may just be the position of the Talley’s when tightened down? I did try tightening them down with a solid bar covering 3 holes; I can do this on all but one screw. That got them really close with the alignment bars. After an hour of messing with it I decided to take a break; think lapping can resolve the issue? This rifle had no issues with the last scope in 1” Talley’s as far as zeroing, I didn’t check level on all of these things when I installed it.

Put the flat end of the bars together and see out of square things are. I no longer use the pointy ends.

As my posts on Tally LW's reflect, I'm not a fan, but when I use them, I lap them. I don't imagine there are too many rail options for Cooper M92's. Is that action straight across the top. I'm assuming so, if you could switch the rings around.

I'd send picks to Tally, before you lap them. I'll bet they sent you a new set of rings with nary a fuss.

This is the correct way to use the bars. Using the pointed ends will tell you nothing.

I'm convinced them pointy ends are best suited for Leupold Dual dovetails.

I am sure Talley rings come from the factory at least as true as manufacturing tolerances allow. The problem is the rifles we mount them on are not perfectly true. You most likely could take those same Talleys and mount them on another rifle of the same model and have different results just due to manufacturing tolerances at different production times, different milling machines/lathes and drill and tap operations used between individual rifles, etc. This is known in the machinist world as "stacking of tolerances". This is true even for a quality manufacturer like Cooper, who I own three of their rifles.

IMHO lapping will not resolve the issue. You will be chasing the pointed tips and not find a resolution. Can we assume the screw hole placement on the Cooper is exact? My conversations with Talley indicate they do not recommend lapping. Keep us posted on the developments.

That and f4$king up stocks.

Welp guys crisis averted...I’m not sure what physics voodoo was going on here, but I am relieved.

So I went backup to the shop after ringman’s Suggestion to use the flat ends. But this time I mounted the rings like this pic, earlier I had first tried in a way that gave me the least ring to ring distance, then inverted that. This time though I did it like this, which will be plenty for my scope and allows the most ER adjustment:



So then I did the alignment bars butt to butt...perfect. I then Used levels on the ring halves....perfect:



I then checked it using the digital level on my phone...I’m not sure why I haven’t thought to use it before. Free app. Anyhow, they are exactly level with each other to 1/10 of a degree. And I rotated the rifle a bit a few times to test, IE they both matched at -0.7, and at 1.1, etc. Torqued them down and they remained so.

Anyhow, thanks guys!

Are the recessed holes for the base to receiver mounting screw heads not finished?

I'd still lap them. They likely pinch in at the top and will mark your scope tube.

I believe I will just to protect the fragile finish on the AMG I have on the way for this rifle.

I see by the fresh aluminum on the screw holes you are radiusing off some of the base material. I see some chattering at one hole too. You need a torx with a deeper "reach" so as not to touch the top edge.

No because just recently Cooper went from 6-48 screws to 8-40. Inc guessing this was Talley’s answer for the rings they had already produced.

The fresh aluminum is from Talley, see my reply to Kingston above.

Your putting a 29 ounce scope in Talley LWs! Get a rail! A low one and some super low rings.

Nice. SMFH

You got any Birchwood Casey AlumaBlack?

I do not. It won’t bother me once a scope is mounted.

One of my failures as a person, among many, I accept

I'm not worried about your failure as a person.

If I have issues with the ocular clearing the LW base I suppose it’ll be time for a rail and rings. Hopefully not though.

Nice Back Country AI Chris. When you get it set up, let us know how she shoots. I guess all that switching the Kimber stocks got old. Enjoy.

I just put talley lightweights on a Kimber Montana 8400 along with a Nightforce SHV 3-10x42. They had to be lapped and the amount of W/E adjustments were just abnormal. I did not have time to go over it again but I will look at it this weekend and probably end up replacing them. Great customer service cannot replace proper machining. This has happened a few times and it is getting to the point that I will not use them anymore after this.

I lap mine. The surface looks flat, but once you start you realize they need some work. I’ve not had a problem with alignment though.

Slight hijack. Most (but not all) action tops are curved to some degree. Most bases are curved to match (ideally a bit smaller radius of curvature so the bases do not touch only on a line between the screws, but on the outside edges.) When you put two surfaces like that together they tend to have a single "best fit" orientation. (I'm simplifying a bit, but not much.) Even if one can get the rings to line up while tightening the base screws with the rings on the bases and held in alignment, this has never seemed to me to be a very robust or stable arrangement. But perhaps it works well enough most of the time.

I have several sets of Talley LW ringmounts. I lightly lapped all of them.

A big honking scope on a svelte rifle!

How does it balance ?

Big honking scope??? Hardly a big scope, it is heavier then most and bulletproof . Balance could be a little better

Form follows function. Do what you like and let the scoffers scoff. That's what they do.

This is the reason I epoxy bed my Talley lightweights to the receiver and do not have to lap them and end up with near perfect scope to ring alignment.

Cut off the heads of 4 mounting screws, coat lightly with wax or a release agent, Wax the top of the receiver and thread screws in with 1/8" to 3/16" sticking out.
Place rings on receiver over headless screws and mount your scope or a virgin lapping bar. remove the scope/ring assembly, thoroughly clean the bottom of the Talleys where they contact the receiver.
Mix the epoxy ( use regular epoxy or bedding compound, not 5 or 15 minute stuff) and coat the receiver contact area of the ringmounts and put the scope/ring assembly back on the receiver over the headless screws. Apply large rugger bands, surgical tubing or electrical tape to hold the scope tightly to the receiver.
Let the epoxy cure for 24 hours.
Tap the scope/ring assembly on the sides of the rings with a taped brass drift punch to break it loose and remove it. Remove the headless screws.
Clean the receiver, new receiver screws and scope base holes. Remove the scope (or lapping bar) from the ringmounts.
Apply blue Loctite to the new base screws and mount and torque down the lower ringmounts being careful to mount them in the same position and orientation as when they were put on with the epoxy.
Mount your scope with the tops.
Now you have as close to perfect ring/scope/base alignment as you can get and without lapping your rings. RJ

I could GAF about others opinions here with the exception of a few individuals.

RJ308 beat me to it. I would add if you have a solid bar of the proper size to use that while mounting and bedding the bases. Saves scratching the scope and is more solid.

Two things about the first photo is that the level is indicating the split or top of the ring alignment. This may or may not indicate the ring contact surfaces are out of alignment, they could even be off in the opposite direction. The other is that bubble levels can be very inaccurate and the smaller they are the more this can be true. Not sure about the phone app. it would be interesting to test.

Lapping won't hurt if not overdone. I also put form a gasket on the rings and the rubbery goop acts like the Burris rings on a micro level to allow for any inconsistencies. Ross Siegfried recommend this and I have not had "ring rash" or a scope come loose since I started using the goop. Either mask the scope with tape or use acetone to remove the excess as soon as it stops oozing otherwise a PITA to get off once it dries.

Is there a recommended torque rate for especially aluminum mounts?

Another thing you can do before bedding the mounts is to lap the bases. Wrap the action in 320 grit paper and the stroke the base over the area of the mounting surface. You can do to the alumina black on the resulting shiny spots but not necessary if set in epoxy. All of this is a bit anal but the whole equation consists of eliminating as many variables as possible. If you do all this you will not have to wonder about the scope mounting.

Well I did some very light lapping, below is my rear rings after a just a few minutes with the lap bar, the rear was the one that I could see a bit of light through and it definitely removed more from the rear than the front. After this I could no longer see any light under the bar or scope tube, and when I mounted up the scope with the turrets centered it was dang near perfect on my collimator with the POI of my previous scope on this rifle.

HOw did it look on the collimator before you lapped? Mine is way off on the collimator and at the range

I did not check. Ever since I've gotten my collimator I've checked the original scope on the rifle before removing it when I swap scopes and then put the new scope at the same point on the collimator, makes sighting in a breeze, usually easily inside 1-2 MOA at 100. Never done it without having to make 3-4 (sometimes more) MOA of adjustment before hand until this scope. Elevation was dead on, moved the windage about 1 MOA.

I am going to go back and redo the lightweights once again and see if that makes a difference. You took off way more material then I did for sure.