FN Herstal Firearms banner
1 - 4 of 4 Posts

·
Registered
Joined
·
20 Posts
Discussion Starter · #1 ·
I used to be in a Marine Scout Sniper team back when i was in the corps and when we used to make wind calls we would use if i recall range in tenths x wind in mph divided by the range constant, my question is each hundred yards from 0-1000 we had a range constant where does this number come from if anyone can tell me because i cant find it on ballistics charts
 

·
Registered
Joined
·
14 Posts
Here is the formula

R x V divided by 15

R=Range in hundreds of yards
V=Wind velocity in miles per hour
15 is the constant number

For 1/2 -value winds divide the answer to the above formula

This is accurate up to 500 yrds.Beyond that you need to change the constant number.

600 yrds divide by 14
700 yrds divide by 13
800 yrds divide by 13
900 yrds divide by 12
1000 yrds divide by11

Estimate wind values

3 mile per hour wind can hardly be felt and cause smoke to drift
3-5 mile per hour wind felt lightly on the face
5-8 mile oer hour wind tree leaves blow constantly
8-12 mile per hour wind blows dust and loose paper
12-15 mile per hour wind small trees sway
 

·
Registered
Joined
·
20 Posts
Discussion Starter · #3 ·
thanx for the reply, i understand the formula and everything but i dont understand where that constant number comes from how is that number found
 

·
Registered
Joined
·
14 Posts
From the ammo if I remeber is where the constant comes from. Some examples I have found. The M118 is where the 15 constant comes from. Now as to who figured these numbers out is a different story. I would guess some Chief Warrant Officer. I know the one we had in our shop at SOI was damn smart.
Hope this has helped. I just got my SS 10X42M mounted to my 22" PBR this mornig and if the wind dies down I am going out to sight it in.
 
1 - 4 of 4 Posts
Top