06-25-2007, 8:45 AM
Quick question what does MOA stand for? I have used the search tool and haven't found the answer.
Minutes of Arc(Angle)
This unit is commonly found in the firearms industry and literature, particularly that concerning the accuracy of rifles. It is popular because 1 MOA subtends approximately one inch at 100 yards, a traditional distance on target ranges. A shooter can easily readjust his rifle scope by measuring the distance in inches the bullet hole is from the desired impact point, and adjusting the scope that many MOA in the same direction. Most target scopes designed for long distances are adjustable in quarter (¼) or eighth (⅛) MOA "clicks". One eighth MOA is equal to approximately an eighth of an inch at 100 yards or one inch at 800 yards.
Calculating the physical equivalent distance equal to one minute of arc can be done using the equation: equivalent distance = 2*tan(MOA ∙ π/21600)*distance. In the example previously given and substituting 3600 inches for 100 yards, 2*tan(1 MOA∙ π∕21600 )∙ 3600 inches = 1.04719756 inches.
Sometimes, a firearm's accuracy will be measured in MOA. This simply means that under ideal conditions, the gun is capable of repeatedly producing a group of shots that fit into a circle, the diameter of which can be subtended by that amount of arc. (E.g.: a "1 MOA rifle" should be capable, under ideal conditions, of shooting a 1-inch group at 100 yards, a "2 MOA rifle" a 2-inch group at 100 yards, etc.) However, ideal performance in a ballistics lab is often very different from real-world results.
Rifle manufacturers and gun magazines are notorious for touting the MOA of their rifles, a common term nowadays being "Sub-MOA", meaning it shoots under 1 MOA. This is often more of a single group rather than an average in order to make their rifles sound better, and often ignores other factors such as rifle recoil (In general, shooters shoot less accurately with a rifle with high recoil than a rifle with low recoil).
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