M&P rear sight adjustment

[wittmeba]

I have an S&W M&P .40 and I am considering adjusting the rear sight. It seems off left about 4" by 2 different shooters. I will do more testing specifically from a more solid bench with bags before drawing any conclusion.

Check & verify my logic:

A pistol with 6" sight radius @ 25 yards (may be less on the radius but for simplicity):

To move the POI left or right 4" the movement of the rear sight would be:

the distance:
25 * 36 = 900"

ratio of sight radius to distance:
6 / 900 = .006667
or
6 / 894 = 0.006711

movement to accomplish shift of 4":
.006667 * 4 = 0.026667
or
.006711 * 4 = 0.026844

Without involving a gunsmith or buying expensive tools, it is reasonable to think that this could be done and measured with a good micrometer? Digital? Has anyone made their own adjustment device to push the adjustable piece in the dovetail?

[Chasbo00]

Without a sight pusher, put the slide in padded vice jaws and use a brass punch and hammer to move the rear sight to the right your calculated distance. I get the same value of rear sight drift to correct for 4 inches left at 25 yards. I use 4/900 = x/6 and solve for x, similar triangles.

[wittmeba]

Thanks for your suggestion and numbers confirmation.