Ring lapping adventures.

[Bushleague]

I've had a rifle for a while that I suspected needed the rings lapped. Finally last fall it was made obvious that something was out with the rings. The rifle was shooting exceptionally well one day, while going over it prior to a hunt I found that the rear scope ring was loose, after tightening the ring back up the rifle's groups opened back up.

So last winter I decided to lap it myself. I used the unthreaded shank of a long 1" bolt, I measured a bunch of them at the store with my callipers and found that they measured between .994 and .996 in diameter, I picked one that was .996. Then I cut the threads and head off the bolt and drilled a 1/4" hole through the shank near the center. I could then use a long 1/4" bolt to turn my "reamer" by inserting it in this hole for a handle. After that I picked up a sharpie marker and some valve grinding compound.

First I used the sharpie to color the inside of my rings, then I put my reamer in and spun it, then pulled the caps (marked so that I did not mix them up or turn them around) and inspected the ink smearing. Sure enough, my rear scope ring was sitting higher than my front, as indicated by a narrow shiny strip at the bottom/ front of each ring. Then I smeared valve grinding paste in the rings, and lightly tightened them down on my reamer. I started slow, but once I got a feel for how much metal I was taking off I started turning the reamer 100x between takes, tightening the scope rings a little every 25 cranks, then doing the sharpie test again.

I didn't ream until I had full contact, I stopped when I had about 50-60% and then re mounted the scope. Just last week I finally got around to taking that rifle back to the range. Bingo... smartened that old rifle right up, it used to group around 2" and now its grouping around 1 - 1.25".

Just thought I'd post this in case anyone else is considering trying to lap their scope but is intimidated or lacks the equipment. Its a pretty simple job and good results can be achieved with very basic equipment.

[cody c]

Nice.


I had a set of 30mm cheap aluminum rings that I lapped, I figured 6 bolt cheap aluminum rings that are well lapped should be as true as more expensive rings.

I ran lapping compound and they were pretty good for wide rings to start with and it worked well... And then my magnification ring wouldnt turn.

The lapping compound took off the paint and smooth'd up the surfaces to where the scope would slowly slide in the rings with recoil, till it rubbed against the magnification ring. I used some epoxy to keep it in place (a vortex crossfire II, nothing too fancy and warrantied) and it worked well after that.

In hindsight the cheap aluminum rings were soft enough to not need lapping and would have held things in place well without lapping needed I believe.

[bobinthesky]

I made my own lapping tool too only I used a stainless steel 1 inch shaft. I drilled a 3/8 hole near the end and put a 3/8 shaft through it for a T handle, it works well.