The "dumbing down of America" - shooting uphill or downhill.

[MCMXI]

RANT ON:

Did anyone watch Sighting in with Shooting USA (February 16th) where they featured the Army Marksmanship Unit discussing how to make corrections when shooting uphill or downhill? SFC Emil Praslick from the AMU introduced two terms.

Straight line distance: The [actual] distance between yourself and the target

Flat ground distance: The actual distance that the bullet will feel gravity's effect as it pulls it to the ground

So what's my beef.? Simple, the AMU's definition of "flat ground distance" is wrong. Gravity acts on the bullet over the "straight line distance" but they must assume that we're all too stupid to understand simple vector math. All they had to say is that we can make an approximate correction for inclines or declines by calculating the flat ground distance and adjusting elevation/windage accordingly. To me, this is similar to telling a new shooter that 1 MOA at 100 yards is 1" rather than 1.0472". We all know that it's close enough for most situations, but why dumb it down? We can handle the truth!!!

I have HORUS Angle Slope Level Indicators (ASLI) on some of my rifles and they simply give me the cosine of the angle from horizontal to the target. They work using the same principle described by the AMU, but it's an approximation that is "good enough" for most situations. However, if you're trying to hit MOA targets at 500, 600, 700 yards etc., it may not be good enough.

The reason why a bullet drops less when shooting uphill or downhill isn't because "it only experiences a gravitational force over the flat ground distance", it's because the component of g perpendicular to the bullet's path is less than g. How hard is that?!!

RANT OFF:

 

[HorseSoldier]

For people learning how to shoot from a TV show assuming they are too dumb for vector math probably is where the safe money goes in the bet.

 

[sappyg]

I don't get it. :banghead:

 

[Jorg Nysgerrig]

To me, this is similar to telling a new shooter that 1 MOA at 100 yards is 1" rather than 1.0472". We all know that it's close enough for most situations, but why dumb it down? We can handle the truth!!!

Why in the world are you dumbing it down to 4 places? That's close enough for most situations., but why dumb it down? We can handle the truth!!!

 

[drkeg]

But the "Flat Ground Distance"/"Straight Line Distance" is the cosine of 20 degrees for the example you drew.

 

[Andrew Wyatt]

Who really cares?

 

[Hendiadys]

I'll go simpler still, when shooting up or downhill, hold a little lower on your aimpoint.

 

[Robert]

Who really cares?

This.

 

[rduckwor]

Perhaps the AMU thought the term "vector math" might be offsetting to the viewers who just wanted to know how to shoot up or down a hill!!

RMD

 

[zstephens13]

So if I'm shooting up/down a hill, do I aim high or low?

 

[dmancornell]

But the "Flat Ground Distance"/"Straight Line Distance" is the cosine of 20 degrees for the example you drew.

Almost, op's picture shows the error between the approximation method and the cosine calculation. It's small but he does have a point i.r.t. the error becoming significant as range increases. It's not rant-worthy and I can find much better examples of "dumbing down" than this.

 

[MCMXI]

Who really cares?

Obviously not you. Well done on that by the way ... very impressive.

 

[30coupe]

So if I'm shooting up/down a hill, do I aim high or low?

Low.

 

[MCMXI]

It's small but he does have a point i.r.t. the error becoming significant as range increases.

At 500 yards shooting FGMM 168gr under standard conditions at an incline of 30° , the error is almost 1 MOA. My only point is that why not preface an explanation with the phrase "we can approximate by ..."?

 

[Robert]

Well done on that by the way ... very impressive.

Not to be that guy, but I have to agree with Andrew. TV makes mistakes all the time, even firearms tv. There is no perfect anything especially tv. The AMU should have known better, I will give you that. Or explained it better. But my degree is in Geography and Environmental Studies so I can't even do the math let alone care about it. All I need to know is hold low.

we can approximate by

And perhaps that would have been the thing to do.

 

[Double Naught Spy]

I agree that it is important to get information correct especially when trying to teach or educate people properly. However, correlating a single mistake of a TV show with the dumbing down of America is equally wrong.

 

[Justin]

When you're shooting in the field, under time pressure, if the approximation is good enough to score the result you're looking for, what would be the point of jumping through the mathematical hoops to get to the same conclusion?

 

[MCMXI]

However, correlating a single mistake of a TV show with the dumbing down of America is equally wrong.

The thread title is a little dramatic no doubt, but if only it were a single mistake on a TV show.

 

[dmancornell]

My only point is that why not preface an explanation with the phrase "we can approximate by ..."?

Probably because the good SFC is simply regurgitating the method as taught by his instructors and he probably has no idea the method is inexact. And since basic newtonian physics is not even covered in high school, do you really expect the exact math to be covered on a TV show?

And since you want to be exact, why not factor in the sine projection of gravity and its positive (downhill) or negative (uphill) effect on bullet velocity?

If I got a dollar for every scientific, mathematical or engineering error on TV, I'd be retired by now. I'm 29 by the way.

 

[BrocLuno]

The flat ground distance is the base of right triangle. What's the big deal? Approximate and shoot. Unless your rifle is 1/4 MOA, there is no wind, the air temp is 65* and you brought your Lead Sled to hold for you - you are in the vital zone if you hold low a few inches at a few hundred yards. Steeper slopes, hold lower. Did I miss something like that mountain goat?

 

[MCMXI]

When you're shooting in the field, under time pressure, if the approximation is good enough to score the result you're looking for, what would be the point of jumping through the mathematical hoops to get to the same conclusion?

I agree with that 100% but that's not the issue. Surely, knowing and understanding the theory and understanding why the approximation is good enough is the better way. In this example, there's a physical explanation that is correct and one that's not. Presenting inaccurate information without prefacing it with "we can approximate by ..." is irresponsible. Just because you know the alphabet, it doesn't mean you can form accurate words, and certainly doesn't mean that you can form meaningful sentences.

 

[BullfrogKen]

At 500 yards shooting FGMM 168gr under standard conditions at an incline of 30° , the error is almost 1 MOA.

A whole 5 inches of elevation? Wow.


If we were concerned with wringing out every last bit of accuracy, we'd bother doing the math. Since it's probably not a concern outside of field conditions, and field conditions being what they are . . . what he described would be good enough.

Just because you know the alphabet, it doesn't mean you can form accurate words, and certainly doesn't mean that you can form meaningful sentences.

There's a difference between book smart, and field smart, too.

 

[MCMXI]

And since you want to be exact, why not factor in the sine projection of gravity and its positive (downhill) or negative (uphill) effect on bullet velocity?

True ... but it's not about being exact. It's about being conceptually accurate which is easy in comparison to the calculations required to calculate the value of g perpendicular to the bullet's path at any given instant. As Justin said, if the end result is almost the same, what difference does it make. The only difference is that you can either go through life being spoon fed information or you can actually think about "stuff". The country is in a financial mess because most people don't think about "stuff", don't understand "stuff" and have the attitude of "who cares?!". But there's no surprise there, most kids in school couldn't even point to Iraq on a map of the world.

I should have known better and not started this thread. I'll get back to work now.

 

[MCMXI]

There's a difference between book smart, and field smart, too.

And as we all know, they're mutually exclusive!!

 

[average_shooter]

No military experience here, just that a few of my friends have spent considerable time on a two-way range. I highly doubt that a DRM or Sniper takes the time to run any calculations when he or his buddies are taking fire.

Knowing how to actually calculate the math is awesome, especially if you're a bench shooter. But it isn't necessary by any stretch, and there's likely little to no time to address it on TV when the point of the show is something else. I'm sure Discovery could spend a whole season on calculating ballistics, but in the end the hunter or rifleman needs to know little more than "aim low when shooting uphill."