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Thread: Mil-Dot Tables for Calling a Legal Moose

  1. #1
    Member highestview's Avatar
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    Default Mil-Dot Tables for Calling a Legal Moose

    Although we've shot 2 spike-forks the last 3 years, we have had to pass on at least 5 bulls who had 3x3 brow tines and seemed to be in that 45-50" range. So darn close, and easy access, just no way to be sure that they were 51" instead of 49". I've looked at that Boone and Crocket rangefinder from Leupold. Many people express high levels of doubt about it, and the $450 price tag is hard to justify. As I have been suffering through high levels of math and statistics at the UAA, a thought struck me. 2 things that are cheap AND reliable: Mil-Dot scopes and trigonometry. Tons of us already own mil-dot scopes. They dont really cost a lot more and they are available in the common variable power ranges that Alaska hunters already use. Generally they are accurate to the mil dimensions and bottom line, they can be checked to ensure that they are. So you still would need a rangefinder, but good quality ones can be had for cheaper and the optimal usable range for the following formulas is from 69.4 yards to 138.8 yards, so you dont need an 800+ yard rangefinder. That range is perfect, too, for approaching moose. Most times, it is possible to get within 70-200 yards of a bull. So this fits within the normal 'spotting range' we already find ourselves in.

    The following will probably bore or confuse many of you. If you trust my calculations, skip to the bottom where I have listed the mil-readings and the distances to achieve 50" or 25". For those of you skeptical, here are my calculations:

    The distance from the center to center of a mil-dot is 3.6000012" @ 100 yards (chuckhawks.com). So a 10 mil-dot scope is capable of projecting a 36.00012" spread at 100 yards. To get the angle that one mil-dot projects, you take the arctan of y/x (vertical change over horizontal change), keeping in mind to convert yards to inches.
    So arctan(3.6000012"/3600")=0.057295779513075 degrees. So 10 mils project 0.57295779513075 degrees.
    I used Matlab to create a table of the angles that the mil-dots create from 1 to 10 mil-dots.
    Now, taking the sine of the angle multiplied by the distance gives you the width.

    The forumula for the relationship of width and distance becomes:

    Width = sine(angle the mil-dots create) x Distance

    So we algebraicly isolate distance, which is the key for this whole thing.

    W=sine(angle)xD => W/D=sine(angle) => 1/D=(sine(angle))/W (inverting) => D=W/(sine(angle))

    So the distance is equal to the width desired (50" or 25") divided by the angle measuring it (number of mil-dots).

    I created a new table, of the width divided by the angle measuring it. So here is what we get:

    -----------------------For 50" For 25"

    Mil-dots used-----(-----------Distance in yards-----------)
    1--------------------1388.889---------------------694.4446
    2-------------------- 694.4456--------------------347.2228
    3--------------------462.9648-------------------- 231.2228
    4--------------------347.2248---------------------173.6124
    5--------------------277.7811---------------------138.8906
    6--------------------231.4855---------------------115.7428
    7--------------------198.4174---------------------99.2087
    8--------------------173.6166---------------------86.8083
    9--------------------154.3271---------------------77.1636
    10-------------------138.8957---------------------69.4479

    So this formula shows that 1 mil dot equals 50" at 1,388 yards, 5 mil dots equals 50" at 277 yards, 8 mil dots equals 50" at 173 yards. Etc. Also 8 mil dots equals 25" at 86 yards, 10 mil dots equals 25" at 69 yards.

    So here's how it works. Say you have a rifle with a 10-mil dot scope and a trustworthy rangefinder. You're hunting in a 50" - 4 brow tine area. You see two bulls sparring about 300 yards downhill from you, behind some spruce trees. This affords the oppurtunity to sneak up to about 150 yards. From here, you can clearly see that both have 3x3 brow tines, but they look to be right in the 50" neighborhood. They have drooping beams, but palms that go more up than out. They are right there in that 'probably legal but not sure' zone.

    (holy cow this sounds like a real life experience of mine, but without this cool formula)

    You set your scope to full power. You would approach 138 yards, using the rangefinder to determine the range. When you're at exactly 138 yards (or 140, see below), you put your scope with 10 mil-dot spaces on him. When he turns directly at you, your 10 mil-dot spaces should equal exactly 50" at his range. You can use this to determine whether he meets the 50" requirement. If you werent able to get within 138 yards, you could range him at 173 yards. Then, you would put the scope on him. At this distance 8 mil-dot spaces would equal 50" exactly.

    Or, lets imagine these two moose are still focused on playing 'Who is bigger?' and actually start walking toward you and get closer than 138 yards. At this point, you switch to 25" measurements. If the rut chemicals push these bad boys to within 69 yards of you, then your 10 mil dot spaces equal 25" eaxaclty. Then, you have to judge one side at a time, from center of snout to the edge of the antler. Or, at 99 yards, 7 mil dot spaces equals 25".

    So there, you have it. All you hunters who already have a mil-dot scope and a rangefinder, you have a method of determining exactly 50" in the field.

    There are still a few asides:

    1.) Common sense/good judgment still applies! It still requires good judgment to tell if a moose is legal. It also takes the determination to walk away if you arent sure. It takes the determination to walk away if it is marginal. We've had to not shoot multiple times now. Remember God see's what is done in secret, and he will punish or reward you for it. Passing on a big moose sucks, but it's worth it to be safe and do the ethical thing.

    2.) You still need a rangefinder. I realize that this method still requires tools that we shouldn't trust fully but this can get us even closer to make a determination. You should probably let a moose that looks like he is 50 1/4" walk. Just like other methods, only shoot him if it's obvious that he is plenty over 50". You cant trust the equipment too much.

    3.) If you use this method, err on the FAR side, not closer. That is, if a moose wanders closer than the listed range, you could get a false positive. If a moose is a few yard past the distances I calculated and appears to be 50" he will actually be bigger than you measure. At 138 yards, the difference per yard is 0.36" That means using 10 mil dot spaces at 140 yards, you're actually measuring 50.39". At 145, you're measuring 52.19", which is a good thing. It forces to measure for more than 50", not right on it.

    4.) This method is only reasonable with a second person acting as a spotter, keeping track of the moose's distance from the shooter. I can't imagine trying to do this by myself. I hunt with someone who would probably be great for this, but not everyone is minded to do quick adjustments like this in the field. Just make sure you have someone trustworthy to help you with this. Be careful of dyslexia. That could really ruin your day trying to do something like this.

    5.) Mil-dots vs. Mil-dot SPACES! Just remember, it takes 2 dots to measure 1 mil. It takes 6 dots to measure 5 mil-dot distances. The distance in question is the distance from the center of one dot to the center of the next, or the center of the crosshairs to the center of the first mil-dot. Remember to use 8 spaces, not 8 dots when using one of the listed distances.

    Well there you have it. You can tell that I've been cooped up indoors too long since last hunting season, but I hope this is useful to some of you. Feel free to print the distances out and bring them with you in the field or distribute, email, whatever to whoever. If someone gives this a try to see how it works, I'd love to know how accurate it is. I will be out to shoot, just not until after finals (ARGHH!), so if some early bird gives it a shot, post here. Tell me how it worked out. If any of you use this to shoot an illegal moose, don't sue me.
    Born in Alaska: The boundary lines have fallen for me in pleasant places; surely I have a delightful inheritance. Psalm 16:6

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    Without looking at the math … I’ve considered the proposed technique to verify moose were sublegal but .. but I'm not ready to adopt the technique "to very that they are legal”.

    The moose rack is 3-D, but the legal requirement is based on a 2-D measurement… so unless you're looking straight on 9like the represent in the example in the hunting regulations), the measurement may be different as their rack has a 3-d Component. Plus, that one tine that gives it the required width might actually be a branch.

    Some people judge moose ... and let the ones walk that are less than 5" of the required width (if its 55+, then potentially shoot). With the proposed technique ... probably consider shaving one inch off that safety factor (eg >54") .. but I'm not so sure that I'd risk the consequences and justify use of the technique on a 51".

    Try the technique on moose racks from different vantage points… and compare those results to the actual measurement. I look forward to hearing what you find.

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    Quote Originally Posted by Wet eNuf View Post
    The moose rack is 3-D, but the legal requirement is based on a 2-D measurement… so unless you're looking straight on 9like the represent in the example in the hunting regulations), the measurement may be different as their rack has a 3-d Component. Plus, that one tine that gives it the required width might actually be a branch.

    Some people judge moose ... and let the ones walk that are less than 5" of the required width (if its 55+, then potentially shoot). With the proposed technique ... probably consider shaving one inch off that safety factor (eg >54") .. but I'm not so sure that I'd risk the consequences and justify use of the technique on a 51".
    I mentioned that, twice. That applies to all estimating techinques. If they look right on the line, you gotta leave em. Also, I said that if the moose drifts further away, then you are measuring with a few inch safety factor.

    Also, every estimating technique requires you to get a straight on look. This technique is no different.
    Born in Alaska: The boundary lines have fallen for me in pleasant places; surely I have a delightful inheritance. Psalm 16:6

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    You made that look way harder than it needs to be. Just put a mark at fitty inches on yur gun from barrel tip to stock. Then wrastle that lil fella down and put ur measure stik on eem! Ifn he's fitty, just choke him out and carry eem back to yur camp for a snack!

    Wut if'n ur range finder is only accurate to +- 1 yard.....? More slack I spose?

    Also - you figured wrongly when you says

    "At 138 yards, the difference per yard is 0.36" That means using 10 mil dot spaces at 140 yards, you're actually measuring 50.39". At 145, you're measuring 52.19", which is a good thing. It forces to measure for more than 50", not right on it"

    If, in fact, your trigonometry (not really upper class math) is correct that 1 yard is .36"....140 yards would be .72 inches more than fitty - actually measurin 50.72 rather than fitty point three niner. But we both really know that it is only .36 inches for that one yard right.......

    Also probably need to factor in the actual size of the mil dot itself as its got a bit of distance within itself.......

    I like the wrastle idea best.

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    This perfectly illustrates my point #1. This technique gives you something you can visually compare the moose with that should be darn close to 50", but you still have to see that he's obviously over 50". Some people (me) just have such a hard time looking at the eyes and comparing that to the side of each antler. I need something like a scale I can visually see and compare his rack to. Now that it's after season, I'm pretty sure the one we passed on was a little bit over 50". I get so self-doubting when it comes to doing the eye-width estimation technique, and probably passed on a legal moose. This is especially problematic for me, since my area seems to be loaded with bulls that are right about 45-50". We have yet to see a really BIG guy, thats obviously over. While we were up there, someone else had shot a moose with 6x5 brow tines that was only 50" exactly. Kind of lame genetics in the particular area.

    I'll definitely be trying this out on some plywood 'antlers' this summer to see how reliable it is. Thanks for the feedback, everybody.
    Born in Alaska: The boundary lines have fallen for me in pleasant places; surely I have a delightful inheritance. Psalm 16:6

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    Quote Originally Posted by highestview View Post
    This perfectly illustrates my point #1. This technique gives you something you can visually compare the moose with that should be darn close to 50", but you still have to see that he's obviously over 50". Some people (me) just have such a hard time looking at the eyes and comparing that to the side of each antler. I need something like a scale I can visually see and compare his rack to.
    Have you considered using a camera? Take a photo when looking straight on .. and judge from the photos you take. Sure beats waiting for the moose to turn his head (again and again) so you can estimate and re-estimate the width.

    Just seems you are wanting a strategy so as to be able to shoot the moose that is 50 -1/8". Have you considered shrinkage? Or that 51 might be <50 when checked by the game warden. But officer, "in the distance the animal was slowly moving away at a slight angle but measured 10 mil dots."

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    An animal with his head at an angle will actually show up smaller than he really is. He is widest when looking directly at you. I like the camera idea.

    I've walked away more than once, I can do it again. I'm not a risk taker when it comes to this stuff. I bet that this year we'll run into one with 4 brow tines and I will have wasted all my time figuring this out.
    Born in Alaska: The boundary lines have fallen for me in pleasant places; surely I have a delightful inheritance. Psalm 16:6

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    THe bottom line is you are taking the time to share something with the rest of us and it appreciated! I loves those that have to look at the half empty aspect.
    Semper Fi and God Bless

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