Thread: Calculating front sight height ? ( maths heavy )

Originally Posted by akaroa1

Bigger brains than mine required for this one

I have just restored a Sharps 1859 Civil War Carbine
It still had the original carbine rear sight ( which is a very challenging POS )
I installed a circe 1873 front sight from another rifle
The rifle has passed proof and shoots an OK group considering the POS rear sight

But it is grouping 150mm above where I would like it to be

So here are the numbers

Range 25 meters

Group wants to shift Down 150 mm

Sight Radius is 530 mm

How do I calculate accurately how much to build up the front sight blade to lower the groups point of impact by the required 150mm

This will be a good formula to have on file because many of the old military and sporting carbines tent to shoot very high anyway

Cheers

It is all about proportions and ratios.

A sight radius of 0.53 m is about 1/50 of the distance to your 25m target.

So if the required change in impact is 150mm, divide this by 50 and you get 3mm.

I'll let you work out if you need to add or subtract the 3mm from the front sight height.