Advanced Marksmanship Conflicting Info on movers. Help!

TresMon

TresMon

Gunny Sergeant
Full Member
Minuteman
Dec 3, 2007
1,241
140
NW USA
#1
Scenario:

We got a mover @ 400 yards moving @ 6mph. Per a certain loads dope:
We need to lead the target 3.9 mils for a full value mover.

But our target is moving away from us at 45degrees.

Per my shooting education- I'm to divide my full value mover lead by .707* to get my lead for an oblique mover. *same sine as for a 3/4 value wind.

However I just came across some text that says mover sines are NOT the same as wind sines. This text I'm reading says for a oblique mover (moving @ 45*) you use half of the Full Value mover data i.e. multiply FV mover data by a sine of .5 .

Which is correct? Why?
 
#2
Re: Conflicting Info on movers. Help!

I think you mean <span style="font-style: italic">multiply</span> the full-value mover lead by 0.707. That answer is correct. In the case of a 45 degree angle, it doesn't matter whether you use a sine or a cosine function, because both the sine and the cosine of 45 degrees is 0.707.

I think the confusion stems from the way you think of the angle of movement relative to the flight of the bullet.

If the angle you are putting into the calculation is the angle between the flight of the bullet and the direction of the mover, then when the angle is zero, i.e., the mover and the bullet are going in the same direction, then you need zero lead for the moving target. A function which gives you zero output for a zero input is a sine function.

On the other hand, if what you are thinking of is the angle between a target moving straight across the line of sight, <span style="font-style: italic">and the angle of the actual moving target</span>, then what you need is a cosine function. And that's the way <span style="font-style: italic">most</span> shooters think about moving targets.

An example:

Let's say I am facing due north. I have a moving target which is moving at 80 degrees relative to true north.

That's <span style="font-style: italic">almost</span> directly across my line of sight, so I'd multiply my mover lead by the cosine of 10 degrees, which is 0.9848.

However the bullet is moving at an angle to the target of 80 degrees, so I'd multiply the full-value mover lead by the sine of 80 degrees, which is, guess what, 0.9848.

So, I think it's simpler to think of it the same way you do a wind lead, and use the cosine function on the angle of the mover with respect to a path perpendicular to the line of the bullet, the same way you do the wind.

And I'll bet that if you look at that text, the writer is using the other method.
 
#3
Re: Conflicting Info on movers. Help!

Are there people who can actually do this in their head, on the fly? I can't imagine doing this in field conditions without having pre-established charts or a <span style="font-weight: bold">really</span> simple rule-of-thumb equation. I can just imagine fiddling about with a calculator and whoops-a-daisy, where'd the target go?

I'm not trying to be sarcastic, so hopefully it doesn't come off that way - it's just that as a civvie down this way, I don't get much moving target practice. The best we tend to get is shooting vermin/pest animals that are moving and then the lead applied tends to be pretty much instinctive. Fire, miss. Correct, fire, etc.
 
#4
Re: Conflicting Info on movers. Help!

As you note, for human moving targets, you're not going to have much time.

Here's one way:

Speed estimation:
Slow walk - 2 mph
Fast walk - 4 mph
Run - 8 mph

Mover rule of thumb: 0.6 mils per mph of target speed perpendicular to the line of fire.

Adjust as necessary for the angle, but realistically, you'll probably just use a full or half angle value, perhaps shaded a bit.

As you note, the best method is to shoot a lot of moving targets - but most people don't have a chance to do that.

A video system training aid for speed and angle estimation could be developed, which would be a real asset for snipers.

Some people just seem to have a talent for movers. Lisa Bynum, the wife of the director of Rifles Only, is one. Rule of thumb for her - in a gunfight with Lisa, stay behind cover. If you move in the open, you're dead.
laugh.gif

 
#5
Re: Conflicting Info on movers. Help!

Thanks Lindy - much appreciated.

I'll take the tip about Lisa Bynum to heart. I'm traveling to the US in March and as part of that trip am scheduled on the PR1/2 course. I'll try not to annoy her.

She did graciously offer to loan me her rifle if necessary. With any luck, it'll be imbued with mover-hitting juju
wink.gif
 
#8
Re: Conflicting Info on movers. Help!

Mover leads need to based or looked at in time of bullet flight and the amount of time of “x” distance the target moves. I think the .5 value statement you read is bovine fecal matter here, where did you read this? Draw a right angle triangle with 10 as a value for both equal sides, 10 being an arbitrary number and not a distance but rather a time for a target covering an amount of distance. Now on the hypotenuse leg establish 10 along that longer line from the start point of the target movement take that point and bring it down perpendicular to the line perpendicular to your line of sight. Mathematically and Professor Lindy is correct that vector is 0.707 or in this case 7.07.
Kind of hard without a diagram hope this makes sense.
 
#10
Re: Conflicting Info on movers. Help!

Movers, now there is a fun activity, also the most common actual sniper target. There are all sorts of techniques from memory drills, to computing speed. Remember, shooting movers much past 600 is mostly pissing in the wind. At those ranges, winds could cause a shooter to have to aim behind the target to hit it.
smile.gif


A technique you can try is to look through your scope and watch the target cross your reticle mil dots. Count to five in one second, takes only a bit of practice. Know your TOF for that range and then whatever number of mils are covered in the TOF based on your count, you pull ahead of you target and break the shot on that mil hold and let the dirt bag hold 175 grains of American technology. Fast, angles be damed, and will usually work with minimal practice and will put a bad guys dick in the dirt.

Lindy as far as something to practice on, I have a 50 meter live fire simulator that will simulate movers out to 1500 meters up to 10mph. It will show the student what his lead needs to be and once the shooter is comfortable the marker can be taken away for more practice. The guys shoot their assigned weapon and ammo in the simulator and it inside out fo the weather. Of course, it is in Beta and we are testing it but it is great with only a few kinks.
smile.gif
 
#11
Re: Conflicting Info on movers. Help!

Rick:

If that simulator is being developed for production, please drop me a P.M. - or an email to my public email address of [email protected] - and let me know who's doing it, when you can without violating an NDA.

I will convey that information to my boss to consider one for our facility, if the price is not totally outrageous. But that'll be his decision, not mine, as it will be his money.
laugh.gif


I saw a note on a nice award you got recently, which was richly deserved.

Regards,
-- Lindy
 
#12
Re: Conflicting Info on movers. Help!

Lindy, I believe the name PRISm and they make all sorts of sims for live fire. I am working on getting rid of the glitches on ours with them as it is a beta for snipers and they do mostly short gun stuff..

Ours cost a mint because it is a beta and has all the bells and whistles, is .50 cal capable, and thus cost 1.4 mil. Ours is also longer at 50 meters than most. Their normal is 25 meters. They have examples in pistol situations for the Navy, Air Force, and RCM in Canada.

It uses interesting technology that I like better than lasershot. Yeah, we have one of those as well for pistol and and AR.

Found this on the internet. h**p://www.mcsira.com/web/8888/nsf/sbs.py?&_id=8686&did=3128&title=shooting%20range%20simulator

One of the pics is inside of the tunnel similar to ours.

Have fun, they will also do videos for branching live fire, I had ten done so we could evaluate them. Some worked well, others not as I had envisioned. Mostly due to the fact that video does not agree with positive ID at longer ranges.
smile.gif


The unit will allow for any weapon that is projected, pistol, rifle shotgun, less lethal. You only input ballistics and the ballistics computer does the rest.
 
#16
Re: Conflicting Info on movers. Help!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: longrange1947</div><div class="ubbcode-body">A technique you can try is to look through your scope and watch the target cross your reticle mil dots. Count to five in one second, takes only a bit of practice. Know your TOF for that range and then whatever number of mils are covered in the TOF based on your count, you pull ahead of you target and break the shot on that mil hold and let the dirt bag hold 175 grains of American technology. Fast, angles be damed, and will usually work with minimal practice and will put a bad guys dick in the dirt.
</div></div>

Thanks Rick! Ultra practical as usual
smile.gif
 
#18
Re: Conflicting Info on movers. Help!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jerry M</div><div class="ubbcode-body">TOF???</div></div> Time Of Flight
 
#19
Re: Conflicting Info on movers. Help!

One thing to remember when using any calc for movers is that the wind will either add or subtract from the value of your lead. Example, I have a lead of 1 mil and a .5 mil wind. If the target is walking into the wind then the wind is blowing off .5 of my lead so I must add the wind call, or my lead is now 1.5 mils. If he is moving with the wind, then the wind is blowing some lead onto my calc so my lead becomes .5 mils. Just remember "against add, with subtract". Again, it is practice.

Simiulator is aimed at military mostly. Guess some LEA, LA County?, could afford these. They should come down in price as they go further into production. The really good things is that I can now show exactly what I mean about mentally moving the reticle away from a friendly or a window frame and missing a shot, or how the reticle drops as it follows the "dirt bag" down but shooter only rises his eye to see the next target and will shoot low because of it. I can over lap targets, change movers and give indicators as to leads, add wind, etc as the studetn advances. WILL NOT replace range fire, but is a great augmentation. I doubted it when it was first explained and tried to prove it wrong, only to be proved wrong myself.
smile.gif
 
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