MOA

[Twud]

If 1 MOA is equal to 1 inch at 100 yards, what is 1 MOA equal to at 200 yards ? 2 inches? What would 1 MOA equal at 1000 yards. 10 inches? Somehow that seems too simple.

 

[Swampy]

If 1 MOA is equal to 1 inch at 100 yards, what is 1 MOA equal to at 200 yards ? 2 inches? What would 1 MOA equal at 1000 yards. 10 inches?

Yes......

Actually, 1 MOA is something like 1.016" at 100 yards, but in shooters parlance it's always just 1" @ 100, 2" @ 200, etc.....

Best,
Swampy

Garands forever

 

[PercyShelley]

There was a thread not so long ago with some really spectacular pedantry, so to save you from that I'll just say this:

Yes, if you work out the trig, it turns out that it really is that simple.

 

[1911 guy]

The numbers really are that simple.

The hard part is getting those 1 MOA groups past 200 yards. For me, anyway.

 

[Bwana John]

While what you have figgured out works well for shooting , it is NOT that simple . If you are not a math nerd dont worry about it .

The short of it is that shooters using MOA are NOT defining a secant line :banghead: (which is what the measurment of group spread on a flat piece of paper is), but it works OK for small arc measurments.

AND a 1MOA rifle @ 100 yds does NOT equal a 10" group using the same rifle @ 1K yds because of other factors not in play at 100 yds (wind, temp, changing BC's, sonic barrier, ect... )

 

[Zak Smith]

1 Moa = 1.0472 * ( Distance In Yards / 100)

 

[Zak Smith]

The short of it is that shooters using MOA are NOT defining a secant line (which is what the measurment of group spread on a flat piece of paper is), but it works OK for small arc measurments.

While technically true, to put this in perspective, there is less than 1/100th of 1% error in the measurement for angles as large as 50 mils (171.5 MOA). In short, you can use this approximation for any angle relevant to rifle fire.

-z

 

[Wes Janson]

Or put another way, if your groups are so bad that the error comes into play, the situation is just plain hopeless to begin with.

 

[Bwana John]

Real men use radians (6.283 not 6.400 )

 

[dmazur]

I think they covered this in high school geometry, if I can remember that long ago. The 1MOA refers to an angle. Think of the target as the base of a triangle. If you have multiple targets at different ranges, you have a series of similar triangles. The size of the base of the triangle is proportional to the distance (the "height" of the triangle.) So, if one triangle with a base defined by a 1MOA angle is twice as far away as another triangle, the base will be twice the size. For shooting purposes, as others have posted, it doesn't have to be any more complicated.

 

[PercyShelley]

While technically true, to put this in perspective, there is less than 1/100th of 1% error in the measurement for angles as large as 50 mils (171.5 MOA). In short, you can use this approximation for any angle relevant to rifle fire.

IIRC, the rotation of the earth becomes a factor before the difference between the tangent and radius fraction becomes relevant. The Coriolis force being, of course, one of the big things to calculate in artillery fire. I recall a story about gunners in a WWI naval engagement missing their targets entirely because the fleet had dipped into the southern hemisphere and they neglected to reverse their Coriolis calculations.