Lapping scope rings

C.Smith · Jul 11, 2011

I have now read or been suggested to me to Lap my scope rings. How does one go about doing that?

Corey

Guest · Jul 11, 2011

You can buy a lapping kit for under $50, and follow the directions, or you can be cheap like me and go to Lowe's/Home Depot and get a 1" oak dowel about 3-4' long that is very, very straight. It may take a while, and multiple trips to multiple stores, but there are straight ones. Or you can get a piece of suitably sized round stock if you know someone who owns a machine shop. Also get some 1000 or 1500 grit wet/dry sandpaper. You'll be using it dry, but I like the wet/dry kind because it holds up a little better in my experience.

Once you get your setup, you mount the bases and the lower half of the rings, and then sit the dowel or round stock in the ring halves. You may also use the dowel to turn in the front ring if you're using a rotary dovetail style mount. Get the rings basically "lined up" with each other using the dowel as a substitute scope tube. Then pull out the dowel, wrap it with the sand paper (tape it in place then overlap it) and place the dowel back into the rings. Place the top halves onto the bottoms, being sure to note which way you have them facing - a piece of tape on top with an arrow to the muzzle works well for this. put the screws in and tighten them just to the point of resistance on the dowel. Gently slip the dowel back and forth in the rings, being careful not to remove too much material. Tighten the ring screws just a little at a time, evenly, and keep sanding, until you have the rings about half tight. Remove them and inspect - if you have uneven sanding in the ring halves, you need to continue a bit, but not so much that you hog them out where they won't hold the scope tube. They don't have to be perfect, but you want about 75% of the ring to be scuffed, at least.

Now, break all the edges on the rings - where they meet at the sides, along the front and back edge of the ring, so that the sharp corners don't dig into the scope tube. Then clean everything with solvent and assemble it as normal. It's pretty easy. Just remember that you can always take more material out of the rings later if you didn't lap them enough. You cannot put it back in.

The entire idea is to hone the "hole" in the rings so that the scope tube has no binding or torque being applied when mounted. The rings still need to be tight, though, so don't lap too much out, or they won't fit your scope tube anymore.

C.Smith · Jul 11, 2011

Okay thanks. Do you find it necessary to do so with all mounts? I just got some Talley light weigths and I'm wondering if I should do that or not.

Corey

IdahoCTD · Jul 11, 2011

I wouldn't use sandpaper unless the round stock/dowel is undersize for the thickness of the paper. You dont want to make the rings oversize on the sides. Most of the material being removed is on the bottom of the rings. I would find a piece of 1" steel and use lapping compound. If you drill and tap the side of it for a bolt it makes it easier to grab.

Guest · Jul 14, 2011

I have a set of Talleys on a Colt Light Rifle, and they are pretty concentric. It is not impossible, though, to mount them "off-center" just a tad, so be sure you mount them via a dowel rod and check them for straightness before you lap them. I did not have to lap the Talleys any, but I did break all the sharp edges that touch the scope tube, just to reduce/eliminate ring marks on the tube. I've not had any issues with lapping my rings the way I've described. The key is, don't take off much material. I've mounted maybe 30-40 scopes this way, and had no ring failures to date.