MOA Used Incorrectly

Discussion in 'General Gun Discussions' started by giggitygiggity, Jan 13, 2021.

  1. daniel craig

    daniel craig Member

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    I usually tell people to a.) Study math b.) many people find mils to be easier conceptually. 1 Mil is 1/1000th the distance to the target whether you’re using yards or meters. At 100 yards 1 MIL is equal to 3.6” and at 1000 yards, 1 MIL is equal to 1 yard.


    But also, that most people don’t need either one, use terms you understand even if that means yards and quarters because it doesn’t matter if your rifle is 1MOA of you can’t visualize it. If you can visualize group sizes at distance based on the size of everyday known objects, use that.


    And no, mils aren’t metric but they do correlate closer to metric than imperial.
     
  2. giggitygiggity

    giggitygiggity Member

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    The point of this thread was to help members understand that MOA is angular and is not simply a synonym for “inches.” I do not assume that everyone is incorrect. I am certain there are some people who understand MOA, but have slips of the tongue. However, I commonly observe people talking about MOA without any understanding of its angular nature; they incorrectly believe that MOA is a word that the shooting community uses to say how many inches wide their group was.

    I did not say that “Angles become invalid at extreme ranges.” I said that “The PRACTICALITY of MOA becomes invalidated when we work at extremes...” The practical aspect of MOA being that if my rifle shot a 1” group of three shots at 100 yards (1 MOA), I can expect that rifle to shoot a 2” three shot group at 200 yards (1 MOA). Whether that perfect 2” group actually happens does depend on other factors (environment, human, etc), but I can reasonably expect a 2” group at 200 yards. Any variation is due to variables (rifle barrel temperature, a slight change in humidity, wind, etc) whose effects become more pronounced at distance. This example is a practical and reasonable application of MOA if I’m shooting a .308. Where MOA’s practicality becomes invalid is at the extremes... at a point, due to the inherent ballistics of that .308, that bullet will stop moving so to expect to achieve any group beyond that range is impractical and, therefore, the PRACTICALITY of MOA is invalid.

    And yes, I completely understand that there are environmental, ballistic, and other factors that will become more noticeable to groupings the further the target is from the rifle. This is where theory meets reality. The theory and what happens if your rifle were to shoot bullets not impacted by ballistic coefficients, environmental factors, and shooter capabilities is that the rifle will shoot a certain MOA at all ranges. I am confident that we all understand that reality often does not precisely reflect the theoretical.

    The bottom line is that to clearly convey performance and to speak precisely, distance to target, number of shots in the group, and the spread of the group need to be told.
     
  3. CapnMac

    CapnMac Member

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    And red-legs use Mils.
    Which are C/6400 per each. Around 0.0565º per each; 3.375 arc minutes per mil; 202.5 arc seconds per mil.
    A milliradian is (180/π)/1000, which runs to near 0.0572º

    US artillery adopted the French mil as the French stopped using decigrades (c/4000) about 0.09º
    The NATO mil is usually specified as 1m at 1km--39.37" at 1093.61 yds (3.2808' at 3280.83')
     
  4. jdh

    jdh Member

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    Mils, radians are imprecise. NATO rounds up to 6400 mils in a circle, BTW.
     
    Last edited: Jan 13, 2021
  5. jdh

    jdh Member

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    Close. 29.1mm or 1.456692913 inches. What, y’all didn’t have to do Trig in metric?
     
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  6. mcb

    mcb Member

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    Radians are as precise as degree, minutes, seconds. Pi is defined by a circle being the ratio of a circle's diameter to it circumference. This is fundamental math. There is exactly 2xPI radians around a circle and an equally exact 360 degrees around a circle.

    Yes NATO rounds 2xPi up to 6.4 "NATO Radians" in 360 degrees but that is for artillery work and does not bear on small arms in any way. A mil based scope is done in actual radians and there is no accuracy gained or lost between doing the math in Radians vs Degrees/Minutes/Seconds.
     
    Last edited: Jan 13, 2021
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  7. Walkalong

    Walkalong Moderator Staff Member

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    Agreed, smaller numbers to work with and tenths, vs say 32 and 9/32 inches.
     
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  8. daniel craig

    daniel craig Member

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    Base 10 is veddy veddy nice
     
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  9. daniel craig

    daniel craig Member

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    Also most people aren’t military and it’s “good enough”
     
  10. South Prairie Jim

    South Prairie Jim Member

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    Well im normally the minority so I guess no difference in asking, couldn't I just divide my poi correction by the yardage ?
     
  11. Skeptic13

    Skeptic13 Member

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    Wow there is a lot of great information in this post. Actually probably more that my brain wants to process so if you see me at the range and I tell you my rifle is shooting 1 MOA at 100 yards please know that what I am trying to say (correctly or not) is that I shot a good group and I am happy with it.
     
  12. lysanderxiii

    lysanderxiii Member

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    Technically, it is not incorrect. I will explain:

    Group size is not perfectly linear with range, however angles are. Just because your favorite shootin' iron can hold one inch at 100 yards does not automatically mean it will shoot 2 inches at 200 or 10 inches at 1000 yards.

    If fact, group sizes generally open up at longer ranges. When ammunition is required to have an maximum extreme spread of 5 inches at 600 yards, and manufacturers are given the option of testing at reduced ranges, say 200 yards, the extreme spread is not just reduced by a third, to 0.278", but more along the lines of 0.25 inch or 10% less.

    So, if you have a gun that shoots 1 MOA at 100 yards, it may very well be that it shoots 1.2 MOA at 600 yards . . . hence, the range qualification is necessary.
     
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  13. Ignition Override

    Ignition Override Member

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    "MOA Used Incorrectly".
    When Rob Ski on Youtube showed 1.65 MOA (3.44 at 200 yards) with his VZ-58, using a Rod Dot scope,

    just Imagine how many people would > Like < for him to be mistaken about his group.
     
    Last edited: Jan 13, 2021
  14. Jim Watson

    Jim Watson Member

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    As said, there are two pi radians in a circle 6283.185 milliradians or so.
    But the military mind doesn't need exact geometry so we had the infantry mil and the artillery mil and various foreigners rounded it off their way.
     
  15. horsey300

    horsey300 Member

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    I won't dispute the underlying point if origin, I have seen/heard this several times myself; I might add that I shot a rifle that on its best day was 3 moa at 50 to 100 yds. On its same best day, it was lucky to hit a 10"target at 250+ changed the loads, and voila! Enter the jbm stability calculator, if the bullet is not stable during flight, the angle will widen from true moa to worse or even keyhole. So in certain (albeit not common) instances, when the speed bleeds off, the angle can grow with lack of stability.
     
  16. JohnKSa

    JohnKSa Moderator Staff Member

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    1MOA is very close to 1" at about 95.492965855 yards. That can be approximated as 95.5 yards without much error--at that distance, 1MOA is about 1.000074"

    Which means, for a very good, but quick approximation of what 1MOA is at any distance, one can divide the range in yards, by 95.5. So 1 MOA at 45 yards is about 0.47". At 250 yards, it's about 2.62".

    Approximation: 1 MOA (inches) is about equal to the range (yards) divided by 95.5

    For those shooting where metric distances are used, 1 MOA is about 2.9cm at 100 meters. Approximating that as 3cm at 100 meters is actually a smaller error (about 3.1%) than approximating 1 MOA as 1" at 100 yards (about 4.5%).

    For a more precise approximation, we can do the same thing we did above for yards & inches. 1MOA is very close to 3cm at about 103.132403124 meters. We can approximate that as 103 meters without much error--at that distance, 1MOA is about 2.996cm.

    Which means that for a good but simple approximation of what 1MOA is at any distance, one can divide the range in meters, by 103 and then multiply the result by 3 to get the answer in cm. So at 45 meters, 1 MOA is about (45/103) x 3, or about 1.31cm. At 250 meters, it's about (250/103) x 3, or about 7.28cm.

    Approximation: 1 MOA (centimeters) is about equal to the range (meters) divided by 103 and then multiplied by 3.
     
  17. Walkalong

    Walkalong Moderator Staff Member

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    Or try to explain to new shooters, 1 MOA being an inch is sufficient.
     
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  18. buck460XVR

    buck460XVR Member

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    :rofl::rofl::rofl: I agree.

    In all my years I have never used the terminology MOA, nor have I ever had anyone around me ever use it. It was always "my rifle shoots X" groups @ 100 yards.". That's probably wrong in someone's head too.
     
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  19. Mark1964

    Mark1964 Member

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    Get involved in long-range match shooting, you'll hear MOA and milirads a bunch.
    Being math phobic, it darn near ran me off ... but I persevered.
    My first two high-magnification scopes have been in MOA, though I'm starting to wish I'd gone milirads. As someone here said, base 10 is pretty nice.
     
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  20. LITTLE BUCK

    LITTLE BUCK Member

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    i agree with arkansas paul
     
  21. mcb

    mcb Member

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    This thread might be an indictment on our country's Math teaching abilities. Didn't we all learn this in high school geometer and trigonometry classes? Now I am an engineer by profession and use this and many other more advanced mathematical disciplines on a nearly daily bases, but I am pretty sure I could have mathematically shown the relationship between group size measured as a linear measurement at a given range and group size measured as an angular measurement at a give range my sophomore year in high school.

    *And before anyone takes offense my own posts are frequently an indictment of our countries Grammar teaching abilities. :)
     
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  22. Legionnaire
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    Legionnaire Member

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    I find that those who are not math whizzes (like me) can visualize a minute of angle fairly easily. From where you're standing, rotate in place until you are once again facing the same direction. You just turned 360 degrees. I can visualize what one degree is, and intuitively understand that the range covered by that one degree is small close to me and large far away. Divide that range by 60 and you have 1 MOA. Again, not hard to conceptualize or visualize. And it is easy to understand that "1 inch at 100 yards" is an approximation for 1 MOA at that distance. I find it easier to conceptualize, visualize, and explain to someone than radians. And once you start thinking in MOA instead of inches, the whole thing becomes moot. But that's just me, and "your mileage may differ." Oh look! Another distance-related figure of speech! ;)
     
    Last edited: Jan 14, 2021
  23. South Prairie Jim

    South Prairie Jim Member

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    It is debatable if anyone can shoot the difference between 3 inches and 3.6 anyway.
    Lol
     
  24. shooter1niner

    shooter1niner Member

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    Next up: How about educating people on what " point blank range " is. I hear people using that term describing the exact opposite of what it actually means...
     
  25. jmorris

    jmorris Member

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    I am not sure if I have ever shot an MOA group with any rifle (they obviously haven’t shot one by themselves). I might be off a tad in distance from muzzle to paper and 1.047” exactly with an unspecified number of shots is a difficult objective to achieve.

    I figure if I ever did it was happenstance and most all of the groups I have fired were either larger or smaller than 1 MOA the further out they go, the bigger they get.

    I can throw volume charges and get sub MOA groups at 100 but with the ES in velocity I can almost assure they wouldn’t have hit a target at 10 times the distance that accurately.
     
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