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# Rifle scopes?

GunsGuitars
Member Posts:

**44**✭✭
What does the MOA stand for when dealing with scopes?

## Comments

1,195✭✭✭✭✭Cheers[:)][:)],

OleDuk

23,656✭✭✭✭Each degree of an angle consists of 60 minutes, and each of these minutes consists of 60 seconds (if you want to take it to the end).

The tangent of 1 minute of angle = tan of .01666? = .000291

tan = the opposite leg over the adjacent leg and the adjacent leg = 100 yards.

Therefore .00291 x 100 yds x 36"/yard = 1.048".

Therefore, 1 minute of angle at 100 yards = 1.048".[:)]

Brad Steele

5,453✭✭✭You're on the right track but it's sin(sine) not tan. Just in case GunsGuitars wanted to fiddle with this formula to figure out other things such as how much to adjust a sight on a rifle...

EDIT:

You're first number the .000291 is correct. Dropped a zero in the second one which would make a huge difference.

23,656✭✭✭✭Don,

You're on the right track but it's sin(sine) not tan. Just in case GunsGuitars wanted to fiddle with this formula to figure out other things such as how much to adjust a sight on a rifle...

EDIT:

You're first number the .000291 is correct. Dropped a zero in the second one which would make a huge difference.

Sandwarrior:

I did drop a zero, the bane of a calculator educated engineer.[;)]

At minutes of angle, using sine or tangent is virtually the same, but, as the angle increases, the more accurate number will be achieved by using the tangent. Sketch it out, the right angle is formed by the straight line to the target and the distance from center. Therefore, the tangent (opposite over adjacent) of the angle should be used, as the adjacent leg is the 100 yard leg. The hypotenuse (used for the sine) is slightly longer than 100 yards, although as noted at these angles, the difference is insignificant at about 0.001".

Brad Steele

16,056✭✭✭I have used 1.047", but taking into account environmental factors and shooter error over distance, I wouldn't think it would make a difference between the two numbers.[^] In any match or shooting situation, where you were zeroed prior to that day, at that distance, your POI will change with environmental changes. It is always a factor of a few clicks one way or another.

GG,..that is what I call "the quick and dirty" explanation.

5,453✭✭✭I guess when I plug your number of .0166666(tan) in I get 2.9088.

When I use sin I get .000291. I'm not trying to be a smart aleck, but by using the base formula you can figure the exact MOA to any range in which you want to shoot.[:)]

The other thing you can do is figure out exactly how much you may need to shim up the rear of your scope to increase your elevation potential.[;)] note: don't do this with two piece bases unless you know how.

JustC,

Yes, we did figure out that 1.047{8} is one MOA @ 100 yds. But once you get to thinking you can't stop.[:D][:D]