- Minute of Angle
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Minute of angle (MOA) is the measurement (in fractions of degrees) of a ballistic round's deviation from its initial heading due to gravity and/or the effect of air resistance on velocity. Informally known as a "Bullet's Trajectory" or "the rainbow effect". Long range weapons must account for this effect because a fired round falls at a quadratic rate. Weapons such as large caliber rifles use scopes with adjustments for elevation and windage.
The exact measure of MOA is 1.0471996" at 100 yards of distance. MOA is a linear measure so 1" of MOA at 100 yards would equate to .5235998" at 50 yards, 2.0943992" at 200 yards, 3.1415988" at 300 yards and so on. Most high-end rifle scopes used by military snipers, law enforcement snipers, and hunters are equipped with MOA adjustment knobs which provide the shooter with MOA adjustment. Depending on the scope, the adjustments are measured in "clicks" of the knob which equate to a manufacturer set adjustment. For example, one click may be 1/2 MOA for every click while another scope may have 1/4 MOA adjustments, which is considered to be a finer MOA adjustment.
Minute of Angle is a linear effect, not quadratic. That is: twice the distance will result in twice the deviation. The value of 1 MOA @ 100 yds is 1.04719758 inches. In linear progression, 1 MOA is equal to 0.52359879 inches @ 50 yds and to 2.09439516 inches @ 200 yds. It is basically the measure of the opposite side of a right triangle with a 1 MOA (1/60th of 1 deg) "A" angle.
See also
Sources
Categories:- Ballistics
- Firearms stubs
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