Advanced Marksmanship High angle/ is this right? FRANK you been there

[2bfarming]

I've ALWAYS heard low poa no matter weather shooting up or down but I have yet to shoot any angle where it made a diff. Here is a quote from another forum

"Just a few weeks ago I did the "High Angle Rifle Training" or H.A.R.T. class at Thunder Ranch. We shot various angles out to 1,280 yards. "Aim low if shooting up and aim high if shooting down." was from Clint Smith's mouth to my ears. It held true for the four day class in the Oregon mountains."

 

[JC Steel]

Re: High angle/ is this right? FRANK you been there

Thats interesting! I was told always hold low

 

[Lowlight]

Re: High angle/ is this right? FRANK you been there

that is not correct, and Clint knows better, I believe it is a mis-quote.

I have participated in several Thunder Ranch HART Classes and it was never described that way.

You always "Hold / Dial Low" as the impact is higher with the angle. Who ever quoted that is incorrect and I suspect mis-understood Clint.

 

[BGE541]

Re: High angle/ is this right? FRANK you been there

The steeper the angle (+ or -) the less distance (in referance to gravitational effect) has upon the bullet. All angles have Cosines. For instance lets say you taking a shot at a mountain goat. You mil the goat, do the math and come up with say 400 meters from your position. You dial in say 8 MOA (say your shooting a 308 Win). You dont focus on your ACI or care about the angle of the barrel (which we will say is 40* in this mountainous area) Alright so your scopes set, you take the shot... and MISS! That trophy Boar is GONE! Why? Because that Goat may have appeared 400 meters away, but the bullet only traveled a "gravitational" distance of...

400 meters x.77 (cosine for 40* angle up OR down)= 308 meters.

So since this cosine is a constant, no matter if you fire uphill or down, the bullet will impact high. So instead of using our said 400 meter DOPE of "8 MOA up" we should have used our 300 meter DOPE of "4.25 MOA up" NO MATTER UP OR DOWN HILL!!!

Now with windage, you would still need to apply your mathmatical formula for the TOTAL BULLET FLIGHT DISTANCE which was 400 meters traveled.

 

[2bfarming]

Re: High angle/ is this right? FRANK you been there

I figured that would be the case. Thanks

 

[Lindy]

Re: High angle/ is this right? FRANK you been there

Actually, it is more accurate to take the dope for the actual distance - in your example, 400 meters - and multiply the dope by the cosine of the angle. To understand why, read this link:

Inclined Fire Explained

In addition, there is a <span style="font-style: italic">slight</span> difference between the drop of a shot up and a shot down at the same angle - which the article explains - but most of the time it may be safely ignored.

 

[2bfarming]

Re: High angle/ is this right? FRANK you been there

How could this have been confused by the individual and still make hits?

The only thing I can think of is the angles are negligable.

From the pics frank posted a while back its hard to tell.

 

[Lowlight]

Re: High angle/ is this right? FRANK you been there

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: brut4c</div><div class="ubbcode-body">How could this have been confused by the individual and still make hits?

The only thing I can think of is the angles are negligable.

From the pics frank posted a while back its hard to tell. </div></div>

For sure most of the angles are not that great at TR, as well depending on the target there is as much as 4 MOA of elevation space to take up... there is also issues with ranging depending on how he determined his range.

But clearly he was wrong, I can email Clint and talk to him about, I speak to Clint at least once a month about shooting and stuff...

But it wouldn't be the first time someone held the wrong way and hit the target because of some other reason

 

[Killer Spade 13]

Re: High angle/ is this right? FRANK you been there

So once you go past 45 degrees up or down where do ya go???

 

[threetrees]

Re: High angle/ is this right? FRANK you been there

@Killer - always below

 

[BGE541]

Re: High angle/ is this right? FRANK you been there

Lindy-

Thats what I was getting with multiplying the distance by the cosine, with the up hill vs. downhill I thought it was splitting hairs for the overall point of this conversation and didnt want to confuse the OP, but good point.


13-

The steeper the angle, the less effect gravity with have the chance to impact the bullet. Mind you, explaining it this way makes sence in my mind and maybe not the mind of others. If you went from a 40* to a 50* and then you would multiply bu .66 to get the distance of bullet travel in regards to your elevation DOPE.

 

[JFComfort]

Re: High angle/ is this right? FRANK you been there

Lindy, I also prefer the improved rifleman rule. Its plenty accurate and fast!

 

[Killer Spade 13]

Re: High angle/ is this right? FRANK you been there

Threetrees,

I'm not so sure of that because once you go past 45 degrees then you start getting into weird things.

If you shoot at a target directly overhead, at 90 degrees, then how low do you hold?

Yes, a rhetorical question . . .

 

[Lindy]

Re: High angle/ is this right? FRANK you been there

If it is a rhetorical question, that's fine. But its analog, that of a shot straight down, is not a mere possibility. It has, in at least one case, been made on a real target. Furthermore, it's a shot which requires computation. There is, in fact, one way to compute that shot for a specified distance, and another way to compute it for an unknown distance. Both methods work for a shot straight up, if it matters.

And nothing gets weird about shots beyond 45 degrees, but such shots at any but short distances are very unusual in the real world.

 

[Rprecision]

Re: High angle/ is this right? FRANK you been there

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Killer Spade 13</div><div class="ubbcode-body">So once you go past 45 degrees up or down where do ya go???</div></div>

POI is always higher becuse gravity has a shorter effect on drop becuse of the bullet path.

 

[Ring]

Re: High angle/ is this right? FRANK you been there

https://docs.google.com/viewer?a=v&p...Y0&hl=en_US

 

[Rando]

Re: High angle/ is this right? FRANK you been there

i learned slope dope with protractor, 550 cord, and a field calculator in the Corps. Then an Army Sniper friend bought me a Horus ACI bubble. easiest thing ever. requires zero thought, just what a jarhead needed !