Here is my method, it’s a SIMPLE Procedure
Drilling and tapping for Peep sight, How to find Dead Center of Tang
This is for education purposes only, You would be doing this with the Tang out of your Rifle of Course! This is just to Show you how to EASILY find Center of the Tang.
First, Measure the width of the Tang, all of the TC’s i have done Measure .500 across, Measure and make sure.
Now that we know the Tang is .500 Across, half of that is .250, Adjust calipers to .250 and Lock them down. With my Stainless calipers i can lightly Scribe a line here. Even if your Tang Measures Slightly Different than .500 just Take whatever the Full width measurement is and Cut that in Half
Now Flip the Calipers over and check from the other side, you will note the Lightly scribed line will match perfectly from this side
This is DEAD CENTER of your Tang.
All that’s left to do now is place the Lyman 57 on the Tang, use the Rear Tang Screw Through the 57 Base, This will Hold it FIRMLY in place, use a pencil and Mark the Front sight Base hole. Now Drill and Tap to 8-32, You can buy this Bit and Tap in a Kit, this is mine
And lastly, Taking the Tilt/Forward lean out of the Lyman 57
First, Push the Button, pull the Slider out and set it aside. The Lyman 57 has a Nice Flat Top surface, use this to your advantage
The Lyman 57 Has a Tendency to Lean Forward, Lay a flat edge on the Top of the Lyman 57’s Flat Base and you will find that it Leans/tilts forward, Like this
Here is How I correct Lean/Tilt (All of my Rifles are like this) I use Stainless Washers that are the Width of the Tang, and the 8-32 Screw will just fit through the Washer hole. On average, I ad 1 washer under the Rear of the Sight Base, and how ever many i need up Front to Correct the Forward Lean, This varies from Rifle to Rifle, You simply need to play around here and get the Base as Close as you possibly can, Being off a tiny bit one way or the other is Fine, all we are doing here is correcting the LARGEST of it.
Here is what i am Looking for, when i place a Straight edge on the top Flat surface of the Lyman 57 Base i want the Straight edge to Run as Close as possible to Straight in line with my Stock/Barrel, Like this