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"Mil", as in milliradian

8/14/2014

2 Comments

 
Everyone thinks that the only thing that the Swiss have invented are Cuckoo Clocks, wristwatches .  .  . and maybe banks, but that is far from true; among other things, the Swiss have to their credit a number of innovations in the science and weapons fields. Obviously when you are a tiny nation in between military powers like Germany, France and Italy you'ld better be VERY well prepared if you want to keep your independence for more than 1,000 years.

Anyway, among the things that military science developed in Switzerland is the milliradian. The root of the "Mil" section in "mil-dots". It was invented by Charles Marc Dapples, around the late 1800's, and by 1914, more than a few countries had already adopted it. France being the first one, as it needed a better sighting and ranging method for their "75" the first truly worthwhile field artillery piece.

Later, in the 1950's NATO standardized to metric units and the milliradian became the standard unit of measure for angle.

So, exactly WHAT is a milliradian? Well, a milliradian is the 1/1000th part of a radian, and before you say: "Dooohhh", let me explain that a radian (rad.) is the angle subtended when the LENGTH along the circumference is the same as the radius of said circumference. This curious definition defines an ANGLE using a CURVED line and a straight line. ¿WHY?, well, Monsieur Dapples was a mathematician and an engineer, and he liked absolute precision in concepts but practical ways for applications; because the relation between a circumference and its diameter is the number "Pi" (also expressed as the greek letter π), that is an endless number, he wanted to be precise but he did not want to write the digits of one number for the rest of his life. So, by using "π" , he was at the same time, scientific and engineering. He was expressing the EXACT relation, but for engineering calculations (slide rules in those days, no calculators and, even less, computers), he could approximate very well (all engineering slide rules have π marked in the scale). So he "discovered" that under the definition of his "radian" as an angle unit, the circumference had 2π radians (remember the circumference of a circle is π x diameter, and that the diameter is twice the radius, so the whole circumference measures 2πr), or ≈ 2x3.141592652xr

From the above, you could say now that if 360º= 2π, then 1radian≈57.2958º, or that 1º≈17.4533 mrads

Up to that point, the UTILITY of the mrad lies only in the manufacture of clocks, where gears and gears and more gears are used to divide the time into the smallest pulsations possible, thereby enabling the clock or watch to be more and more precise; BUT, ¿HOW did the mrad jumped to artillery and then to riflemen usage?

Well, we need to understand at least ONE concept of trigonometry: the sine.

Before you get scared, look at this picture:
Picture
It is a simple "right" triangle. It is called "right" not because all other triangles are "wrong", but because ONE of the angles is 90º (or a "right" angle). In the picture the greek letter Θ ("Theta"), stands as the name of the angle we want to work with, and because the angle is a CONSTANT RELATION between the LENGTHS of the Hypotenuse and the opposite sides, then knowing this proportion allows us to "scale" up and down the triangle and ALWAYS keep the same relation between those two lengths. Conversely, if we KNOW the VALUE of that proportion and we know ONE of the lengths, then we can calculate the other. 

One of those relations is called "sine". And it is defined as the length of the opposite divided by the length of the hypotenuse:  

sine(Θ)= opposite/hypotenuse

Now, imagine that the opposite side was a section of a circumference whose center is the corner where the Θ letter is located, it would not be straight, but it would have a length. If that opposite side was the SAME length as the "nameless" side in the diagram (usually called the adjacent, but let's leave it as "nameless" for fun), then the LENGTH of the opposite would be the SAME LENGTH as the radius that generates the opposite (the "nameless" length), and then Θ = 1 rad.

Now, here comes the magic, and because I do not want to bore you with more maths, let's look at a table:
Picture
As you can see, expressed in more conventional units:
sine(90º)=1.000
sine (75º)=0.966
sine (60º)=0.866
sine (45º)=0.707
sine (30º)=0.500
sine (15º)= 0.259
sine (0º)= 0.000

BUT (always a big BUT somewhere!, LOL!), when expressed in radians:

sine (90º≈1.57rads)=1.000 (difference between rads and value of sine = .57)
sine (75º≈1.31rads)=0.966 (difference = 0.34)
sine (60º≈1.05rads)=0.866 (difference = 0.18)
sine (45º≈0.79rads)=0.707 (difference = 0.083)
sine (30º≈0.524rads)=0.500 (difference = 0.024)
sine (15º≈0.262rads)=0.259 (difference = 0.003)
sine (0º=0rads)=0, difference ZERO.

We therefore KNOW that for SMALL angles the angle in rads and the sine of the angle have almost the same value because we have analyzed that the differences become smaller and smaller.

IF the angle in rads (or millirads, to use the "zone" we are talking about) has the same value as the sine of that angle, then the original definition of sine above:

sine(Θ)= opposite/hypotenuse

Can also be expressed in more useful terms: Hypotenuse = Opposite/sine(Θ)=1000 x Opposite/mrads

If we translate trigonometric terms to shooting terms then:

Range = 1000 x (known dimension of target / mrads) and the mrads is what we measure with the marks of our scopes' reticules (when the reticule is either First Focal Plane, or set at its "true" magnification).

For example: If I know that my target is 1 yard high (a small Roebuck) and the whole animal can be fitted between the centers of two consecutive dots, or between two consecutive unit hashmarks, then I know that buck is 1,000 yards away. If said buck occupied TWO dots, then it is 500 yards away, if it occupied 4 dots, then it is 250 yards away (now it is a doable shot at such small quarry).

Of course, if I know that my zero is at 250 yards, then I can take the shot with "no hold" (either over, under, left or right), but if I know where my trajectory is at all distances, then I can hold to the EXACT point where I KNOW I will hit the target. I can ALSO allow for wind.

This is the "principle" of bracketing, this is WHY it works. There are plenty of writeups in the web about the usage of mil-dots in different units, different configurations (Army vs. Navy), different reticules, formulae and even places where you can buy the modern version of a specific slide rule, called the Mil-Dot Master that makes Imperial Unit users get the numbers right. 
I will not go there. For me it is dead easy because I am metric and in metric units if you express the height or width of an object in milimeters, and use true dots or hashes, you get directly the range in meters.
What is almost non-existent in the "Imperial Units" shooting literature is how to measure, set, or ensure that your mil-dot scope (or variations thereof) IS truly useful, or not. So let's get into that, using one of the excellent AEON scopes, an 8-32X50:

Because the relation between range and target size starts from a basic relation of 1:1,000, you need to find a place where you can set a construction ruler (one of those squares/rulers that are used to mark and and cut gypsum board) at 83 feet and 4 inches (83' 4"). ¿Why that specific distance? simple! there are 1,000 " in 83' 4"; and the rulers and squares we are talking about come marked in inches and fractions thereof.

So you need to setup something like this:
Picture
At the "target" end you need something as simple as this:
Picture
After setting up with the metal tape, I always reconfirm the LOS distance with a laser distance meter (not a shooting rangefinder, a laser distance meter or laser measuring tool) because there is no way I can hold the tape taut enough to ensure that the distance is truly what I need when I work alone. Perhaps doing this with a buddy might enable you to hold the tape taut enough. Then you sight in and focus your scope:
Picture
If you are famliar with the scope brand and reticle design, then you know more or less where in the mag ring the scope's reticle will be "true", that is a good starting point.

And then you fiddle with the mag ring till the most extreme marks in your reticle align with the inch marks in the ruler. Sometimes it takes more than a little fiddling, but patience here will yield huge rewards later, as you will be CONFIDENT of what you are measuring with.
Picture
As you can see from this picture the top hashmark aligns with the 34" marking on the ruler, the next full unit mark aligns with the 33", then the "zero" aligns with the 32", the next full unit down aligns with the 31", the next down with the 30" and the last one with the 29" (when doing precision work use one SIDE of the white line marking in the ruler, as opposed to the center of the -usually- thick line, this will ensure better consistency).

Do note that in this scope, the sizes of the marks are VERY consistent, even across half of the field of view of the riflescope.

This is not common in "economy" scopes and it is one of the reasons why we like the AEON brand of riflescopes.

Also note that for every full unit mark, the AEON scopes have 4 intermediate marks, thereby allowing us to measure not only in mrads, but in ¼ mrads and estimate up to 1/8 mrads.

The greater resolution in the measurement AND in the hold-off are very important in Field Target, especially when shooting in the southern clubs of the US of A that love tiny Kill Zones.

In case you have one of the economy scopes that are "true" at 10X, but you have, at least, up to 12X magnification in your zoom ring, you still have one more thing you can do:

First ensure that your reticle is TRUE at 10X using the above procedure.

Then move the ruler to the 100' line and set your magnification at 12X, you SHOULD see that the dots in the reticle and the inches in the ruler coincide. This is because at 12X, the reticule is no longer mrad, but it does measure IPHF (Inch Per Hundred Feet) angles, and the approximation of sine to length still works. So you CAN use your 12x/true at 10X scope to do the ranging and the hold, BUT you need to ensure that the field of vision is FLAT (the last distance between dots measures the same as the first one), and you would be wise then to use your range card in feet, not yards.

Hope this helps!






HM
2 Comments

Preparations to go to New Zealand II

8/9/2014

2 Comments

 
As promised, as the items are finalized I will try to keep everyone posted.

Thanks to the generous support of PYRAMYD AIR , we were able to embroider the "uniform" polos and hats:
Picture
The Team's "theme" for this year, replicating the pins.
Picture
A detailed view of the "theme".
Picture
The Cap
Picture
A detail of the Cap's back (for picture identification).
Picture
THANKS, Pyramyd Air!
Because of time constraints we will take all the uniforms to New Zealand and distribute them there, except in the case where we find the opportunity to hand deliver them before.
This year there was no consensus on pellet sponsorship, so that is something we will need to work on next year.
And there are other aspects that need taking care of. 
As the Team matures and grows, I am sure that it will be more appealing to other shooters to make the special effort to be part of the International FT scene.
2 Comments

The II Cross Catskills Challenge

8/5/2014

0 Comments

 
One of our "new" traditions within the Minutemen Field Target League has become the teaming up between two different Clubs to make a Grand Prix event happen.

As most of you know, an AAFTA sanctioned GP event needs to fulfill some conditions, mainly:
More than 100 shots over two days
Be advertised well in advance
Have a minimum Average Troyer Difficulty Rating of 30
Each course must have at least 10 positional targets.
Have a minimum of 15 TWO-DAY shooters
Have a minimum of 20 shooters each day.

In reality, if a GP is put together, it is not at all difficult to exceed the attendance numbers. It IS almost impossible to keep all shooters happy when they see what a 30 Troyer course is REALLY like! LOL!

At these two legs we had 32 shooters on the first day and 26 shooters on the second day.

Airgunners are gluttons for punishment, we know that. And based on that knowledge, I will foist on you, dear reader, a little more punishment by writing this entry. Of course it is a secret that AAFTA will take this entry as the "Official Match Report", so I cannot be as colorful as I would like, but, we need to be multi-purpose.

;-)

Some stories truly start at the end, this one didn't. For days we had seen the weatherman (oopssss, sorry, not PC enough!!!!!!); weatherpersons go back and forth with predictions for the weekend that ranged from sunny and hot to deluges and thunderstorms to make Noah balk. It was SO bad, that it prompted one of our MD's to post a note in the forum:

"The match will be held no matter what the weather conditions are so all attending please check the weather forecast and prepare accordingly."

Luckily, our rabbit's foot proved as reliable as always (though not in my personal benefit) and the luck for good weather held. Varied and challenging, but no rain.

We started day one at Broome County's Sportsmen's Association's excellent High Power range to do our registration and sight-in:

Picture
LOTS of targets at correctly measured distances, to ensure that everyone is right on track.
Picture
The WV contingent.
Picture
From left: Larry Bowne, Paul Bishop, Jerry LaRocca and one half of the Canadian Contingent: Mr. David Bartlett One PCP among all springers!
Picture
Ray Apelles in his usual fine form.
Picture
A more general view, with one of the Deans of Airgunning in the US, Mr. Hans Apelles in his "Unlimited Class" rig (high chair, high bipod, high magnification scope). With a blue shirt, the other half of the Canadian contingent, Mr. Brian Milne
Picture
Can you hear their conversation: "Are ya sighted in?" "Well as much as I will ever be" "Let's get some bug juice on this arm" "Hmmmm. . . nice, but ¿can we get started, please?"
Picture
So, adjourn we did to the range, 11 lanes here under the tarp. 4 lanes outside.
Picture
The 4 outside lanes.
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One of our Juniors, showing fine form and dedication.
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The eldest of our Juniors. It has been nice to see Nick evolve as the years go by into a dedicated, serious shooter. I am sure we will see a LOT of him in a few more years.
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The Man of the Day. Jerry LaRocca posted match high. Here he is displaying a fine style for kneeling shots.
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Undoubtedly, one of the most interesting personalities in FT. Todd Banks is a champion Benchrest shooter, he VERY recently switched shooting sides for visual accuity reasons, he was being constantly jibed as "lefty". But he never lost his style nor his smile. A privilege for the League to have him with us!
Picture
Kevin Kunkle displaying a fine shooting style and using his new D54 rifle.
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When they stop horseing around, the Canadians are quite serious! Not that they can stop for more than the 4 minutes, JUST what it is necessary to take the 4 shots!
Picture
My better half, Veronika Ruf
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A talented shooter and stockmaker, Paul Bisho[ uses a minimalist approach. No jacket, no gloves, no special shoes, he and his trusty HW98 usually post very good scores.
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Another of our Juniors. These are the seeds that will make FT grow, we are indebted to those that bring them to the shoots, that tutor them, that sponsor them, thanks to the parents, friends, uncles and everyone else. As my father in law says "it takes a village to raise a child", and shooting is no different.
Picture
Paul Manktelow seems to be thinking "Did anyone see me hit that?"
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A very happy Glenn Thomas, he has nurtured and fostered his son Glenn into a good shooter (and amateur gunsmith who just might change the "amateur" part soon).
Picture
Our own Tom Wade, one of the staunchest supporters of the Crosman Discovery.
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Whether you believe it or not, in this head is where the Minutemen League idea got started. ;-)
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Mr. James Wilcox to the left and Mr. Thomas Holland to the right.
Picture
Sometimes we do take ourselves seriously, ¿no?
Picture
One of our brave Match Directors, Mr. Gregory Shirhall
It was a tough shoot. There was wind and then there was absence of wind. There were times when there was a wind in the back, but none at the firing line. In certain parts of the range, the wind entered from the left, in others from the right and in others still, it was in your face or at the back of your head.
A few very dark targets added to the challenge and when a dark target is placed at the extreme limits of the allowed distance under cover of trees and with an overcast sky, it was TOUGH.
But still, some shooters shot better than others and when all the points were counted, these were the standings:
Picture
And so, Day 2 started at the Eastern Field Target Competitor's Club with the normal sight-in. Because the airgun range is a self-contained affair, sighting-in is done with paper targets in the lanes. We try not to put paper target near the FT's and so far, we have observed a definite advantage to sighting in under the same conditions of the Match.
Picture
Another of our brave MD's, Mrs. Pat Shirhall
Picture
An up-and-coming shooter, Mr. Shawn Leonard. He has only been shooting FT a few months and he is already placing among the top.
Picture
The firing line.
Picture
Picture
Picture
In the early morning, the camera had needed the flash to take these pictures, by mid-day, it was dappled light all over the place!
Picture
Can you say "dappled light of the forest"?
Picture
You can almost hear James Wilcox thinking: "If I was William Tell, I would be reserving a pellet for the Match Director . . . "
It was a challenging shoot. The difference in light changed the scope rangeing marks more than 8 yards in my case. I had to revert to stadia-rangeing, or bracketing, to get some reasonable distances.
After loosing a few points that put me back on track.
It was not temperature oscillations, as the temperature had not changed that much. It was the amount and orientation of the incident light.
As usual, I experienced a few challenges, like having to take two shots kneeling because the target's KZ was not visible, from my very low shooting position:
Picture
But I nailed them, so no biggie. I lost two further points by shooting the elevated targets out of sequence, LOL!
My squad mate, Matt Brackett had bigger problems, he was simply not "in the groove" that day. He usually beats me, but more than a few things were not in their place.
Picture
Always a pleasure to be squadded with Matt Brackett, one of our future Spring-Piston values for the World's circuit.
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My usual squad mate, Mr. Arthur Deuel, always a gentleman, he never looses his good temper and nice style.
In the end, the Match proved that good preparation, training and attention to detail will most surely take the day. 
The Match high score was posted by a WFTF PCP shooter, Mr. Thomas Holland, and the second best scores were posted by a Hunter PCP tied with an Open Piston shooter: Mr, Bill Day and Paul Bishop respectively.
Veronika posted a personal best, shooting 81% of the Match High. Overall, she would have posted the third highest score of the day.
Congratulations to all high shooters!
Picture
Last year, the awards ceremony was hurriedly conducted on pain of getting REAL wet! LOL! this year we had some time and we all enjoyed the banter.
The winners were:
Picture
The new members of the "75 yards Club" From left: Shawn Leonard, Harold Schaefer, Bill Day (twice), Larry Bowne (with a 0.22" springer shooting 13 ft-lbs), and Kevin Kunkle (with a springer shooting 12 ft-lbs).
Picture
From left: Paul Bishop, First Place Open Piston Larry Bowne, Second Place Open Piston Skip Teney, First Place Open PCP
Picture
From Left: Paul Manktelow, Third Place Hunter Piston Greg Shirhall, First Place Hunter Piston Kevin Kunkle.- Second Place Hunter Piston
Picture
From Left: David Bartlett (Canada) Second Place WFTF PCP Thomas Holland First Place, WFTF PCP Brian Milne (Canada) Third Place WFTF PCP
Picture
From Left: Jarry LaRocca First Place WFTF Piston Ray Apelles Second Place WFTF Piston Veronika Ruf Third Place WFTF Piston
And some more pictures:
For those interested in the stats, here is the sorted by difficulty layout of the whole 102 shots match:
Picture
And for those that are interested in who shot what:
Picture
ENORMOUS Thanks have to go to Pat and Greg Shirhall for all the effort to setup the BCSA leg and for the collation of all the targets' BTDR's. Also thanks to Hans and Ray Apelles for all the effort to setup the EFTCC leg.
Thanks to all the shooters for their continued support of the League and its events. Some drove considerable distances to attend and it is sincerely and greatly appreciated.

And thanks to the Love of my life, my wife, Veronika, without whom I could not do half of what I can do when she is around.

Now that the party is over, there is only one thing that we can possibly do: Start planning the next one!

Hope to see you all somewhere in some lane, sharing an FT course.

Un abrazo!







Hector Medina
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    Hector Medina

    2012 US National WFTF Spring Piston Champion
    2012 WFTF Spring Piston Grand Prix Winner
    2013 World's WFTF Spring Piston 7th place
    2014 Texas State WFTF Piston Champion
    2014 World's WFTF Spring Piston 5th place.
    2015 Maine State Champion WFTF Piston
    2015 Massachusetts State Champion WFTF Piston
    2015 New York State Champion WFTF Piston
    2015 US National WFTF Piston 2nd Place
    2016 Canadian WFTF Piston Champion
    2016 Pyramyd Air Cup WFTF Piston 1st Place
    2017 US Nationals Open Piston 3rd Place
    2018 WFTC's Member of Team USA Champion Springers
    2018 WFTC's 4th place Veteran Springer
    2020 Puerto Rico GP Piston First Place
    2020 NC State Championships 1st Place Piston
    2022 Maryland State Champion WFTF 
    2022 WFTC's Italy Member of TEAM USA 2nd place Springers
    2022 WFTC's Italy
    2nd Place Veteran Springers
    2023 WFTC's South Africa Member TEAM USA 1st place Springers
    2023 WFTC's South Africa
    2nd Place Veteran Springers

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