Formulae for calculating proper front sight regulation?

[ConfuseUs]

I have an M91/30 and an M-38 which shoots very high at 50 yards. I measured the front sight posts of each and established that the heights are the same. The rear sights, although of different designs, are also the same height off the barrel centerline at the 100M setting. Since range time is expensive for me I was wondering if a formula derived using similar triangles is appropriate for calculating the proper amount the front sight post must be raised. Here is my formula:

P1 = (D1/D0)*H0 + P0

Where
P1 is the proper height of the M-38 carbine front sight post
D1 is the distance from the rear to front sight on the M-38
D0 is the distance from the rear sight to the target
H0 is the vertical deviation of POI from POA at distance D1
and
P0 is the height of the M91/30 rifle front sight post


So, is there a better method to calculate the proper front sight post elevation? I assume that bullet trajectory isn't relevant to this problem because the long rifle doesn't shoot horrifically high at 50 yds. (in geekspeak, the M91/30 has H0 = 0)
I also goofed with the numbers a little at work and established that an error of +/- 1 yd for D0 is relatively minor.

 

[Bwana John]

Using the theorem congruent sides of similar triangles are in perportion I get a slightly different formula.

(delta P1= the change in front sight height needed to zero rifle)

delta P1/D1=Ho/Do
OR
delta P1= D1 * Ho/Do

I would think that trajectory IS very important!!!

I find actually going to the range and regulating the sights by emperical evidence works much better than figguring out formulas at home.

 

[ConfuseUs]

Yeah, you have the formula for delta P0 only; my formula is for P0 plus delta P0.
I would like to calculate the closest approximation because I need to remove the front sight base and install a new front post. I've heard of some quick and dirty ways to extend the post, but I have my doubts about them.

 

[gezzer]

Get a Brownells catalog They have a chart that works. It may also be on line.