The standard symbol for marking the arcminute is the prime (′) (U+2032), though a single quote (') (U+0027) is commonly used where only ASCII characters are permitted. One arcminute is thus written 1′. It is also abbreviated as arcmin or amin or, less commonly, the prime with a circumflex over it ().
The subdivision of the minute of arc is the second of arc, or arcsecond. There are 60 arcseconds in an arcminute. Therefore, the arcsecond is 1/3600 of a degree, or 1/1296000 of a circle, or (π/648000) radians, which is approximately 1/206265 radian. The symbol for the arcsecond is the double prime (") (U+2033). To express even smaller angles, standard SI prefixes can be employed; in particular, the milliarcsecond, abbreviated mas, is sometimes used in astronomy.
The sexagesimal system of angular measurement unit value symbol abbreviations in radians (approx.)
degree 1/360 circle ° deg 17.4532925 mrad
arcminute 1/60 degree ′ (prime) arcmin, amin, , MOA 290.8882087 µrad
arcsecond 1/60 arcminute ″ (double prime) arcsec 4.8481368 µrad
milliarcsecond 1/1000 arcsecond mas 4.8481368 nrad
microarcsecond 1 × 10−6 arcsecond μas 4.8481368 prad
[edit] Uses
[edit] Firearms
The arcminute is commonly found in the firearms industry and literature, particularly that concerning the accuracy of rifles, though the industry tends to refer to it as minute of angle. It is popular because 1 MOA subtends approximately one inch at 100 yards, a traditional distance on target ranges. A shooter can easily readjust their 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 group size equal to one minute of arc can be done using the equation: equivalent group size = tan(MOA/60) × distance. In the example previously given and substituting 3600 inches for 100 yards, 3600 tan(1 MOA/60) inches = 1.047 inche
Dale S
I apologise for what is happening to this forum as of late.The Supermoderators must have abandoned us but I see Robert Whitley has edited his posts.
If your range is 200 yards you can sight your rifle dead on at 200 yards.To find out if your scope will work at 1,000 yards see if it will go up 200 clicks if it has 1/8 minute clicks in it.If it has 1/4 minute clicks in it see if you have 100 clicks up.
As you can see from the Wikipedia post I included the difference between inches and minute of angle is not worth worrying about.
If your dead on at 100 yards your bullet at the sacramento range will be about 275 inches low.If your dead on at 200 yards your bullet will be about 263 inches low or a difference of about 1.4 minute of angle.
Again once your all dialed straight on at 200 yards let us know how many clicks you have left.
Lynn
