View Full Version : Lapping rings question

October 30, 2004, 07:49 AM
I am a bit new here...sorry for what is likely and old question...I just bought some PRI rings and Picatinny rail base for my Rem LTR .308...should I lap these $130 rings. :confused: If so, how do I do it or should I send it to a gunsmith? Thanks...

October 30, 2004, 02:22 PM
There is a scope ring alignment tool available, basically two cylinders (one for each ring) and sharpened to a concentric point on one end. Clamp each cylinder in one ring, and if the points are pointing right at each other you're in the clear. You can get these from Brownell's and Midway.

Personally, I have always honed rings to correct even teensy errors, but most of the scopes I have owned have been over the $1,000 range.

October 30, 2004, 05:02 PM

"If all bases, rings, and actions were manufactured in perfect sync with each other, mounting a scope would be a piece of cake. Whether you use a one-piece base or two-piece base, the odds are generally against you that they will be in perfect alignment. If you ignore this status and tightened your new $800.00 scope in your misaligned rings, the result is that you will cause the scope tube to actually bend to match the misalignment of the scope rings. This will put the inner workings of the scope in a bind. Our lapping tool will help alleviate this problem.

The lapping tool consist of a steel bar of correct dimension to fit your rings, a handle and some lapping compound (enough to do about 5 sets of rings). This tool is used to remove metal from the scope rings where it is causing the tube deflection. This procedure actually puts the bearing surface of each ring in alignment with the other.

When a new scope leaves the factory it is optically centered. Problems with alignment that are not corrected require you to adjust the scope using the elevation and/or windage knobs. Excessive movement may cause the image to be distorted or create a negative parallax condition. Extreme amounts of adjustment to correct or misaligned rings and bases also tend to hamper the scope’s light gathering qualities, thus making the sight picture darker.

The other thing to look for on your bases is to watch for clearance underneath. If your base is not fitted perfectly flush to the receiver you may want to think about shimming the base to allow it to seat properly. We recommend two-piece bases in most applications. Some people argue that a one-piece base adds strength to the action. Do you really think a 5” long piece of thin aluminum or steel is going to provide much strength to an action?

The Sinclair lapping tool takes a little bit of elbow grease but is a relatively simple procedure to perform and we provide plenty of good instructions."

They also make a 30mm tool. John

October 31, 2004, 08:22 AM
Thank you mikikanazawa and johnbt...I am mountinhg a Swarovski in PRI rings and bases...so I will do as you suggested...

November 6, 2004, 10:47 AM
Correctly made rings and bases make lapping unnecessary. Unfortunately so few manage it. Check out Tactical Precision for the best in rings and bases. if you use someone else's rings and bases, they have a solution too.


November 6, 2004, 09:21 PM
This article for Real Guns may help.


Good luck...


November 7, 2004, 01:00 PM
GREAT article on scope mounting... I am a real stickler for the proper use and preloading of bolts, and this article is 95% spot-on. (I would leave the fasteners dry instead of oiled when using a torque wrench.)

I liked the discussion about squaring the reticle too.

November 9, 2004, 09:05 AM
Thanks JoeHatley for that article...I got my scope mounted and it is sighted in as well...evn used an inch lb. torque wrench that I borrowed from a friend.
Using the string hanging to set the reticle straight was invaluable to me.... :)