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Question on sight height math


Kenj59

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Ive got an X5 and mine is shooting high, which seems to be opposite of most other owners. I've read in another thread about X5 front sight height someone was doing the math to determine the correct height needed based on distance to the target and how far the shot was off target. Can someone enlighten me on the formula used or a chart available to figure this out? Thanks!

 

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I use the “Law of similar triangles” as it will give a clue. Trig works too but KISS…

 

This assumes that there is no trajectory drop due to gravity. At close ranges that is often good enough for government work. (So… say pistol caliber inside of 25 yards? that might be ok…all depends on your particular requirement... rifle caliber at 300 yards? no way, gravity is a bitch and she will be satisfied)

 

1. Determine your “sight radius” i.e. the distance between your front sight and your rear sight. I measure the distance between the rear of the front and the rear of the rear because that is what my eye focuses on although I often just assume 3”, 4” or 5” depending upon a particular gun because that will get you close.

 

2. Determine the amount you are low or the amount you are high at the distance you are concerned with. For example: let’s say you are 2 inches low at 25 yards.

 

So you need a front sight that will raise your POI 2” at 25 yards and your sight radius is 5".

 

So the equation is: x”/5” = 2”/25 yards

 

Solve for x and convert yards to inches and you get:

 

x” = (2”/5”) / (25 yards /( 1 yard/36”))

or

x” = 0.0111…”

 

So you would need a front sight that is approximately 0.01” lower than what you have now.

 

Or: just call Dawson and let them do all the dirty work, lol

Edited by ddc
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28 minutes ago, Kenj59 said:

That's what I was looking for. I want to understand the calculation if I need to do it, but I'm glad to know I can be lazy and use the Dawson calculator too!

 

Yes it is nice to know the background. If you punch the same numbers I used in my example into the Dawson calculator you end up with the exact same answer.

 

I didn't compare results before I posted the calculation. I probably should have and I'm glad I didn't give you something bogus.

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