Advanced Marksmanship Rule of 9s (wind holdover)

[Lindy]

Re: Rule of 9s (wind holdover)

People's brains work in different ways. What works for one person may not work for another.

My rule is to use what works for me.

For example - moving targets. With a .308, I use a moving target lead of 0.6 mils per mph of target movement perpendicular to the line of sight.

A slow walk is about 2 mph. A very fast walk is 4 mph.

Is that exact? No. You have to estimate the speed of the target. Human targets rarely move for very long at consistent speeds.

The target may not be moving perpendicularly to the line of sight. And you have to take the wind into consideration, increasing the lead by the wind hold if the target is moving into the wind, and decreasing it by the wind hold if the target is moving downwind.

(I do everything in mils - because I hold, and that's what the reticle is graduated in - so I use the wind formula for mils I posted previously.)

But for people who haven't shot movers very much - which is most people - it's a place to start.

 

[Sterling Shooter]

Re: Rule of 9s (wind holdover)

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Priest</div><div class="ubbcode-body">Take it easy mate. This was a good, collegiate thread until you sounded off. There's a fine line between pointing out reality and coming off as both patronising and condescending. You seem to have enough time to chime in on the , maths when it suits you. I don't see anyone here claiming it to be a realistic solution when under a time crunch.

Pshell's point was well taken, and well delivered.</div></div>

Yes, Pshell's post was indeed right on it, and that was my point..mate.

 

[Bill Larson]

Re: Rule of 9s (wind holdover)

from my competitive LR shooting and hunting experience....
I`ll go with super aviators come up sheet...KISS
bill larson

 

[Sterling Shooter]

Re: Rule of 9s (wind holdover)

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body">People's brains work in different ways. What works for one person may not work for another.

My rule is to use what works for me.

For example - moving targets. With a .308, I use a moving target lead of 0.6 mils per mph of target movement perpendicular to the line of sight.

A slow walk is about 2 mph. A very fast walk is 4 mph.

Is that exact? No. You have to estimate the speed of the target. Human targets rarely move for very long at consistent speeds.

The target may not be moving perpendicularly to the line of sight. And you have to take the wind into consideration, increasing the lead by the wind hold if the target is moving into the wind, and decreasing it by the wind hold if the target is moving downwind.

(I do everything in mils - because I hold, and that's what the reticle is graduated in - so I use the wind formula for mils I posted previously.)

But for people who haven't shot movers very much - which is most people - it's a place to start.
</div></div>

Lindy, you're a smart guy. You have a big brain. You clearly use it, and it shows. You have both the capacity and facilities to perfect your marksmanship skills for any arena/condition. What I appreciate about your statements most is they are supported by facts, as well as experience. This is refreshing in a forum where too often popular culture just circles the wagons, precluding any ideas from getting out alive. Yes, brains work differently, but some, it appears, don't work as well as yours, or are not getting as much exercise as yours.

 

[Lindy]

Re: Rule of 9s (wind holdover)

Not everyone can do math in their head, particularly quickly, or under stress.

For those, an aid like the one below is useful. It's a chart with ranges in yards down the left, and wind speed in MPH in the columns. The data is wind hold in mils, for a full-value crosswind for my .308 load.

I did that in an Excel spreadsheet, but it takes little time to work one out by hand using a ballistic program like JBM.

Use what works.

 

[Sterling Shooter]

Re: Rule of 9s (wind holdover)

I think just about anyone with an IQ over 77 can indeed do the math, if the math is for an outcome in MOA, and which uses the constant of 10. Perhaps, that's why it's taught in SDM class that way. You know, so folks can get a good hit quickly and under stress. Certainly, pulling out a chart, or looking at anything else for that matter which will take the eye off the sight is not going to get a good hit any quicker.

 

[_S2_]

Re: Rule of 9s (wind holdover)

Thanks for all the great info/feedback guys.