A forum member sent me this a while back in response to my question about how to calculate how much metal to take off of a barrel shoulder to get the front sight indexed to 12 o'clock.

A lot of interesting stuff in this thread... I hope this info helps to add to it.

"Setting the shoulder back to get the sights to index involves a little calculation with the threads. You need to know how far the barrel advances with one turn of the thread.

To determine this you take 1.000 and divide it by the pitch of the thread ( number of threads per inch). An easy example would be if you had a 20 pitch thread (20 threads per inch).

Doing the division comes up with .050" and that is how much the barrel advances per one revolution.

If a sight indexed at 6 o'clock to get to 12 o' clock, it has to rotate another 180 degrees, removing .025" from the shoulder would do that per the math.

In practice, removing .022-.023" would allow for a little crush fit to bring the sight up to the desired position and have enough tension to hold the barrel in place. If it doesn't quite index you can always remove another .001-.002". If you go too far, you have to take it a full turn and start over again".

Math was never my strong point, so figuring out how much needs to be removed from the shoulder to rotate the sight by some odd number of degrees completely strips my gears.