KD Distances vs. 25m vs. MOA

[PaleRider]

I'm not sure this question belongs here, and I'm new, but why do we shoot the "simulated" AQT and sighters at 25 meters rather than 25 yards? Everything else we see and talk about uses the English system of measurement (KD shoots and IMC). In fact, if we are telling students that the 25m sighter targets simulate a 1/4 distance to a 100 yard target, it's not really correct. If we tell them that at 100 yards a MOA is ~1" then at 25 yards a quarter-inch is ~1 MOA, not 25 meters. The difference in MOA is not much, but we don't seem to be consistent in our math when discussing the topic. 1 MOA at 100yds is 1.046" while 1 MOA at 100m is about 1.14" (2.9cm) as you all probably already know.

Most of us understand the math of this discrepancy (I'm assuming), but I'm a little concerned about mixing this up with the home-school groups since we may be giving them somewhat of a math lesson as well.
Thanks,
Tim

[Fred]

  Tim, the simple answer is that 25 meters is what the original AQT reduced target was set up for, by the military. That goes back at least 50 years (prior to that, it was 25 yards - and prior to that, I'm thinking, was the "1000-inch range").

  We could switch to 25 yards, but it would require resizing the targets and frankly doesn't seem worth the effort, considering the major focus of every volunteer in the program should be on filling those empty slots on the firing line.

   The rifleman in field shooting is used to fudging things - see the 'Quick 'n Dirty Wind Rule' - so arithmetical consistency should not rule everything else.

    What rules us - or should rule us - is the Mission of Appleseed.

    Come up with a solution to all those empty slots, and you can write your own ticket in this program - including requiring all the targets to be resized for 25 yards!

   No criticism intended in any of the above of your OP. Simply trying to answer the question raised in the simplest fashion. Your service in this program is much appreciated.

[PaleRider]

Thanks, Fred! I've only been to a few Appleseeds, but no one has really pointed out that there is an actual difference. Home-schooled children tend to be pretty damn smart. So what's your take? Should we go into the difference if one of them wonders the same thing as I, or should we just go ahead and address it since a geometry/trig lesson is tacitly part of the event?

[EZ3]

As a recovering homeschooler I have to concur with your opinion, PR.  If'n it was me, I'd wait to see if anyone questioned it.  If they do, DEFINITELY turn it into a "teachable moment".  For example, "What is the difference, in inches, between 25m and 25yds?  100m and 100yds?  500m and 500yds?"

[Hop]

I've wondered this myself because I've done several Appleseed KD shoots.  Most of them at Camp Atterbury (http://www.campatterbury.in.ng.mil/) but one in Evansville, IN (http://redbrush.org/).  Even though it's an active military base, Atterbury's range berms are setup in 100 yard increments.  I don't know why an active military base wouldn't be using Meters.  It's too hard to move all the berms I guess???

Redbrush was flat, no berms.  The farthest shooting pad is at 500 yards.  We could have shot at 100 Meter increments there but were told we were shooting yards there too.

As far as I know we did 25 Meter sighters at both locations.

[TJ Kackowski]

The approach I'm using when presenting the IMC segment is to explain that since we're already flooding their minds with lots of new information, that we don't need to add any more stress due to complicated math ... soooo, for today and today only, 1 MOA = 1" at 100 yds, and to further relieve stress, 1 meter = 1 yd that way the 1/4" grid on the 5-square target = 1 MOA.

If anybody wants to delve into the real mathematics behind IMC, I offer to take it up with them during a break.  Got my HP-11C all ready to do some serious number crunching (anybody remember old houses are homes of angels?). 

People who truly understand the math behind all this also understand that the average person just doesn't really care for anything more than the simplified version.

After all, isn't our rifleman standard 4 MOA?  Do we really need to concern ourselves with the numbers behind the decimal point?  Does anybody have any glass or iron sight that can even adjust for the numbers behind the decimal ... even with the cumulative effect at long range?

Like Fred pointed out, what's our goal?  To transform this country into mathematicians?  Keep it Simple and always be able to back up what you're teaching.

[MostlyHarmless]

we don't need to add any more stress due to complicated math ... soooo, for today and today only, 1 MOA = 1" at 100 yds, and to further relieve stress, 1 meter = 1 yd that way the 1/4" grid on the 5-square target = 1 MOA.

Ding ding ding!

Right in one. Don't make this more complicated than it needs to be. We're introducing enough new material that important stuff can easily get lost going over unimportant stuff. We must make and use practical approximations where appropriate- and so we do.

I too am very happy to go over trig and geometry (and ballistics and mechanics and meteorology and...) with any student who wants to go into it- but not at the expense of time and focus away from the stuff that we are there to teach.

I would love to see this become a nation of mathematicians once again- it would help address some other pressing future problems our society will face. But we're here to make a nation of responsible citizens. Best not to lose focus on that.

[Charles McKinley]

As a current Homeschooler I can tell you that they are more than capable of ROUNDING i.e. a meter is approximately a yard.  I use the wavy equals sign. As stated above the sights aren't capable of adjusting to behind the decimal point and most sure aren't able to shoot it.

I worry about this as much as I do explaining the coriolis effect and other irrelevant material that is outside of the POI.

KISS:  Keep It SIMPLE Stupid

Most people glaze over the first time they hear IMC so get through it for those that get it and answer everything else when it isn't holding up the line.

[AFTERMATH]

If they ask, just state:

"That is an excellent observation!  But Riflemen keep things simple and this is close enough."

Remember:  A minute of angle itself is not exactly an inch at 100 yards.

[DEH]

While technically it does make a difference (small) as the targets are 7 feet closer at 25 yards,  the big purpose of the 25 m/y zero is to get a preliminary zero.  The rifle is not considered truly zeroed until the zero is confirmed at full distance.

Like someone before me said:  ..simple and close enough.

[Big John]

It doesn't really matter, as said above. The targets are scaled for 25 m, and, although the square targets
and the sight adjustments will not be quite as close to 1/4 inch clicks, I'd be more concerned about the
target scale being off.

Plus, 25 yards would be easier, and who would want that?

[jmdavis]

 The old  1000 inch ranges were 83.33 feet and 1000 inch matches ran well into the 1970s. More recently, military sight in and alt-c qualification take place at 25m.

Until you get to 300 meters the differences between meters and yards are not that significant with modern ammo and rifles. You could run the ballistics for 62 and 77gr ammo to see what I mean.

But remember the value of 25m shooting is immediate feedback. You don't need expensive spotting scopes and you don't need to spend a lot of time walking to check targets or make pit changes.

[PaleRider]

All,
I guess I wasn't clear in where I was going. I wasn't concerned with the actual shooting distances and whether or not it made a ballistic difference. I was more concerned with the homeschoolers. We are giving them a trigonometry lesson in addition to what our actual emphasis is (heritage and marksmanship). Some of them are pretty young, and I don't want them to get confused when we talk IMC (total English system), but yet they see 25m on the sighter. Many of them may not know what the difference is (don't assume anything when teaching). Also, when I was young (Carter years), we were beaten over the head with the metric system. The US has seemed to have given up on that (especially highway signs).

As has been stated earlier, it makes sense just to talk English system for IMC and then at the end have them realize that we're actually shooting about 7 feet further due only to how the CoF for the AQT has been set up.
Tim

[V]

Excuse me, inches, yards, pints, gallons (real ones) are the "English" system.... This metric you speak of is those damnable Europeans and that diminutive Napoleon.

To understand the beauty of human based measurement I recommend the John Quincy Adam's report to congress on weights and measures.

A great resource for homeschoolers too: science, history all wrapped up in one free online available pdf.

Cheers
V

[MostlyHarmless]

I guess I wasn't clear in where I was going.

That may still be the case. I don't understand your concerns about homeschoolers.

Teaching IMC is not a lesson for kids on geometry and trigonometry. It is an application of geometry and trigonometry, for people who already have an understanding of them. If a shooter doesn't have an understanding of it, they're not going to get it from us. And we cannot teach it to them. If a homeschool kid, or public high school kid, or anyone else is inspired by this application to seek out a greater understanding of these subjects, terrific. But this is not and cannot be a focus of our program.

Our lessons are on history and marksmanship- with an implied lesson on citizenship. To somehow take on responsibility for anything else weakens our ability to get across the message we are there to spread.

[PaleRider]

@V, LOL!

@ MH,
I greatly disagree. We are also, whether we like it or not, setting ourselves up as potential examples for these kids. They learn from EVERYTHING they see. Granted, our main foci are heritage and marksmanship, but whether we like it or not, we are teaching a trig lesson in that block. We don't need to disenfranchise any parents by appearing not to know our subject.

Anyway, I appreciate all of the comments. I'll just suggest to our SB that we handle it as a "teaching moment" and get it right regardless. It's been hammered out enough here  .


Thanks,
Tim