Technical Information

Columbia Precision

Installing the Columbia Precision Tang Peep Sight

The Columbia Precision Tang Peep Sight is designed to fit a number of different rifles made by several manufacturers. It will fit all pre-64 Winchesters and their facsimiles. Henrys, the models 1866 and 1873 may take two small mounting screws, as there are holes in the upper tang for both mounting screws. All the other models use only one small mounting screw and a slightly longer tang screw with a slightly smaller diameter head. These small mounting screw holes are typically filled with a plug screw which must be removed. Different bases are needed for New Winchesters with thumb safeties.

The distance between screws (both configurations) is 2.180”, center to center (O.C. or “on center”). The length of tang screw and the thread size varies from model to model and between manufacturers, so, it is important to be sure to have the correct mounting screws. When ordered for a particular make and model, screws are shipped with each sight. If no maker is indicated, Winchester screws are packed with the sight.

Sharps rifles have a slightly longer distance between mounting screws (most are 2.260” and Pedersoli is 2.250”), but use two small screws. However, these are a different thread (10-28) size from Winchester, and do not interchange. Brownings, as well as many recent manufacture Winchesters and others, do not have the forward mounting screw hole tapped into the upper tang. Caution should be taken when drilling and tapping this hole. The proper size tap is a 3/16 - 36 NS (Brownells does not usually stock this tap. However, Field Tool Supply Company in Chicago does. Their phone is 312-541-6500, and they will ship on a credit card). We encourage that this  be done by a competent gunsmith-machinist.

When mounting the sight in properly aligned holes, start both screws without tightening either one down. When both are well started, tighten them each down a little at a time until secure.

The Columbia Precision Tang Peep Sight has a windage element which allows for adjustment side to side. However, some arms will not have a perfectly milled or aligned upper tang . When the sight is mounted, it may not align with the barrel or barrel sights. If this occurs, and the mounting is to be more or less permanent, shimming of the sight base may be necessary. Some old timers would use anything from cigarette papers to matchbook covers to raise the sight base on one side to straighten the post to the gun. Others might strike the sight with a mallet to “bend” it into position. Although paper won’t hurt anything, we suggest the mallet not be used. The best way to shim the sight base is to cut (ordinary scissors will work) 1/8” wide and 2” long strips of steel shim stock (.005” thick) and lay them in position under one side of the base. Generally, three such shims, one on top of another (held together with a drop of rubber cement), will solve most problems. This can be done with mounting screws loose enough to slide shims  under the side of the base, out of sight. The elevation post, which holds the aperture, will always have some rotation or “looseness” to it. The amount of looseness will vary from sight to sight, but it will never rotate more than about 5 degrees. This amount is not visible to the eye when using the peep, so is not a problem when shooting, and does not affect accuracy.

Installing the Columbia Precision Tang Peep Sight on New Winchesters

For the New Model 1886, a hole should be drilled into the top of the upper tang using a 5/32” bit (.156”) or, preferably, the same size end mill. Then a flat bottomed tap should be used for cutting the threads. This hole should be a maximum of only .125” deep. The thumb safety is attached to the bottom of the upper tang with a screw which penetrates the tang .125” from the bottom. Although this screw hole and the front mounting screw hole are not in exactly the same place, the holes may overlap, and the screws interfere, if either is drilled too deep. The thickness of the tang at this  point is slightly more than .250”. The thumb safety mechanism should be removed before drilling and tapping the front mounting hole for the tang sight. For the New Models 1892 and 1895 there is no interference with the safety (it has a shorter base, so the supplied base may need to be shortened) and the mounting screw hole may be drilled and tapped all the way through the upper tang. The mounting screw hole is just .500” in front of the upper tang screw, and does not interfere with the safety mechanism at all. When mounting the sight in properly aligned holes, start both screws without tightening either one down. When both are well started, tighten them each down a little at a time until secure.

​The Winchester New Models of 1886, 1892 and 1895 all have a thumb safety on the upper tang. Columbia Precision makes a sight base especially tailored to accommodate this safety on the Model 1886. It is slotted to allow access to the safety through the sight base. For the 1892 and 1895 a base will need to be shortened so as to not interfere with the safety. Care must be taken in drilling and tapping the front mounting screw hole, as it is not cut at the factory like pre-war Winchesters. 

Tang Peep Sight Elevation/Windage Calibration, Aperture

There are small, white dots on the back of the elevation posts (side toward the action), seven on the Tall Post and four on the Short Post sight. On the top of the elevation nut there are four marks: three white and one orange (or possibly red or yellow), readily viewed in the elevation post notch. As you screw the elevation post up (clockwise), it takes two complete turns of the nut to move up one white mark. That means basically eight “clicks” of rotation get one white elevation mark. So, there are about 50 measurable, recallable settings on the Tall Post sight and about 26 on the Short Post,  before you run out of post. These calibrations are all equally spaced at .075” apart.  They serve to let a shooter return to a previously recorded sight setting for a particular powder measure, bullet weight, range or combination of all of these factors. They may also be used for re-setting when and if the sight is moved to a different gun.
Windage adjustment is made by loosening the lower, smaller knurled nut at the bottom of the elevation nut. It only takes a slight turn counter clockwise to do this (and the elevation nut may not work with the lower nut loosened). With the lower nut loosened, the post, which is attached to the windage cylinder (calibrated and visible through the two overlapping holes in the  block), can be moved left or right. When the desired position is reached, the post and cylinder are locked in position by tightening the small nut back down (clockwise). With the lower nut snugged down the elevation nut will again function. With the post centered in the block, the peep should line up with the barrel sights. If it doesn’t, it means that the tang may be bent or imperfectly milled, or the barrel may not line up exactly with the receiver. If you plan to leave the tang peep sight on a gun with this condition, it is suggested that you shim the sight base so it does line up with the barrel sights. This procedure is discussed in the installation instructions.

​​The target aperture provided is a .850" knurled disk with a .035" sighting hole. It is removable and has a 7/32' X 40 thread size, which is a common Lyman thread, among others. The "ghost ring" (threaded hole with aperture removed) measures about .190".

Tightening the Post In the Sighting Position

The sighting post will automatically set itself in the upright position by means of a slight detent between the windage block and the ears of the sight base. The post is held in the base by a cross screw. That cross screw is slotted to be tightened or loosened with a dime or a penny. The sight may be held firm in the sighting position by snugging this cross screw. Without snugging, the post my rebound out of detent with recoil from heavier cartridges. If you remove the cross screw, you can see the groove detents on the inside of the base ears. You can also see the stainless steel detent screw in the windage block. We do not recommend fixing the sight post in the upright sighting position, as with heavy recoil, the post may come back toward the shooters face. The light detent is designed to “give” so serious injury will not occur. However, if an experienced shooter wishes to fix the post in sighting  position, he may do so by snugging the cross screw.

If you have questions, by all means call or email.

Columbia Precision

P.O. Box 301, Timnath, CO 80547 Ph: 303-808-2007