Sight Adjustment Formula

[bradshaw]

Three measurements allow precise adjustment of iron sights. I prefer to measure sight radius on a handgun to the nearest thousandth-inch. Absent a caliper, the nearest 1/10-inch may be plenty accurate. To the nearest inch is better than nothing.

All measurement in INCHES
1) Distance to target.
2) Sight radius----distance between sighting surface of front & rear sights.
3) Error----correction needed to move POI (Point of Impact) to POA (Point of Aim).

Formula
SIGHT RADIUS X ERROR divided by DISTANCE = SIGHT ADJUSTMENT.

EXAMPLE: Ruger 03, 5-1/2” bbl
1) Sight radius----7.247-inches (Jim Clark rear sight; Super Redhawk front sight).
2) Distance to target----600-inches (50 feet).
3) Error----4-inches.

7.247” X 4” divided by 600” = 0.048”. In this example, to move Point of Impact 4” at 50-feet, move rear sight 0.048-inch.

Move rear sight in direction you want shots to go. (To adjust front sight, front sight is moved opposite where you want shots to go.)

Micro-adjustable rear sights have different click values. Bo-Mar, the benchmark for consistency, averages .002” per click. Numerous sights average .003 to .004” per click, with some more coarse. Accurate measurement of click value is best made with a dial indicator. Gun must be rigid in a vise, with rigid indicator. Take measurement on SIGHT PLANE of rear sight. A warped or inconsistent elevation screw makes inconsistent adjustments. Adjustable sight should be lubricated with non-oxidizing oil.

Silhouetters and match shooters learn to guesstimate clicks for instant adjustment at long range. To “hold Kentucky” works for a few shots, but consistency suffers over an extended period, as the mind plays games.
David Bradshaw

[bigbrowndog]

Another way to say how to adjust the front sight is to move front sight to wear shots are Impacting. Rear sight is adjusted to wear you want shots to go.

David, I’ve got more of your posts copy/pasted to my notes more than anyone else’s. From trigger jobs to leather conditioner, it’s all good stuff.

Stay safe.......Trapr

[contender]

Another excellent, to the point, easy to understand post. Must be why I can understand it!

[webber]

Another way is the radian method which is simple.
4÷600×7.247=.0483128. Walaa.
Works every time. Took about 3 seconds.
Just try it with different examples to check it out against other ways.

[weiler]

This is very interesting stuff, I populated the data below from JBM ballistics, and worked backwards to determine the approximate number of "clicks" I would need to make sighting adjustment to various ranges (assuming that while 1 click = ~1" at 50 yards, it would equal 2" at 100 yards,4" at 200 yards etc) on my 5 1/2 Ruger 45 Colt. I have yet to test this on the range to see if it holds water, but I want to incorporate this formula you provided and see it its jives.

Distance to target 50 yards 1800 inches
Sight radius 7.5 inches
error 4 inches
adjustment = 0.016666667
Each Click (inches/clicks)

0.002"     8.333333333 clicks
0.003"     5.555555556 clicks
0.004"     4.166666667 clicks

Might try rigging up a dial indicator to test,interesting to see if 1 click does indeed equal .004" of sight adjustment on my stock Ruger sights

as always, appreciate the education

[bradshaw]

Apr 24, 2020 11:45:02 GMT -5 weiler said:

This is very interesting stuff, I populated the data below from JBM ballistics, and worked backwards to determine the approximate number of "clicks" I would need to make sighting adjustment to various ranges (assuming that while 1 click = ~1" at 50 yards, it would equal 2" at 100 yards,4" at 200 yards etc) on my 5 1/2 Ruger 45 Colt. I have yet to test this on the range to see if it holds water, but I want to incorporate this formula you provided and see it its jives.

Distance to target 50 yards 1800 inches
Sight radius 7.5 inches
error 4 inches
adjustment = 0.016666667
Each Click (inches/clicks)

0.002"     8.333333333 clicks
0.003"     5.555555556 clicks
0.004"     4.166666667 clicks

Might try rigging up a dial indicator to test,interesting to see if 1 click does indeed equal .004" of sight adjustment on my stock Ruger sights

as always, appreciate the education

*****

Weiler.... while introducing math, be aware most revolver sights are more coarse than: “... assuming 1 click = 1” at 50 yards... 2” at 100 yards...”

Just yesterday, Bill Fowler and I were talking about ammo and sight dope for handgun silhouette. Experienced silhouette shooters can provide some guidance, but real sight dope must be established using the individual gun and ammo on the Firing Line. Guidance saves time and ammo, but does not replace the need to throw lead.
David Bradshaw