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April 22, 2009
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So, while working up the front sight blade for a project, I was struck by the fact that I'm not quite sure how the heck they work.
Let's take a model 14-2. The front and back sights are fixed, so when you line up the sight picture, you're going to be hitting bullseye at X# feet.
Now let's change the shrouds. The sight blade is the same size, so now the sights are for N# ft, correct?
Where's the math to figure out what your distance is?
Obviously if your front or rear sights are adjustable, all this doesn't matter.
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Range Officer
Range Officers
May 2, 2009
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Option 1:
1.Shoot a group (at least three shots) with the current front sight. This can be done from any known distance. Convert the range to inches. (i.e. 100 yards is 36X100 or 3600 inches)
2.Measure the distance the center of the group is from the desired point of impact in inches.
3.Measure the distance from the front sight to the rear sight in inches. This is called the sight radius.
4.The change in height needed is calculated by multiplying the desired change from step 2 by the sight radius in step 3 and dividing by the range (in inches) that the group was fired at from step 1.Â
   For example:
   Let's say our rifle shot 10 inches high at 100 yards and the sight radius of our rifle is 23 inches. We can calculate the amount of change we need in the front sight as follows:
Change =Â 10 inches X 23 inches = .064 inches or about 1/16 of an inch.
               3600 inches
Now to order a front sight the correct height, You measure the height of the front sight on your rifle from the bottom of the dovetail to the top of the sight, add the change calculated above and ask for that height. Use a caliper or micrometer to measure with since you need to have an answer in thousands of an inch.Â
Â
Option 2:
Use the following equation to determine the height change you need to make:
Sight change = Sight Radius X_ Impact distance
Sight radius: Distance between front and rear sight
Impact distance: Measurement from point of aim to bullet impact
Target distance: Measurement from muzzle to target
Sight change: Amount of correction needed
Sight rule: Move rear sight in the direction you want the bullet to move. Move front sight the opposite direction you want the bullet to move.
