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-   -   What is MOA? (http://www.firearmstalk.com/forums/f65/what-moa-47941/)

navvet08 09-08-2011 01:29 AM

What is MOA?
 
I know that MOA stands for minute of angle. What exactly does it mean? And is 1/8 better than 1/4 or is it the other way?

canebrake 09-08-2011 02:08 AM

Using and Understanding Minute of Angle (MOA)

NOTE: You should understand that an English inch and a Minute of Angle (MOA) is not the same thing. (That disclaimer is to avoid me going all engineering on you. Should you want some additional info, see post # 10.) They are units of measurement that to avoid obfuscation, are close enough together that for the rest of this explanation I will simply round down to an inch.

Exact Minute of Angle (MOA):
1 MOA = 1.0471996 inches @ 100 yards.
1 MOA = 5.24 inches @ 500 yards.
1 MOA = 10.47 inches @ 1000 yards.
Rounding MOA:
1 MOA @ 100 yards = 1 inch
1 MOA @ 200 Yards = 2 inch
1 MOA @ 300 yards = 3 inch
1 MOA @ 400 Yards = 4 inch
1 MOA @ 500 yards = 5 inch
1 MOA @ 600 Yards = 6 inch
1 MOA @ 700 yards = 7 inch
1 MOA @ 800 Yards = 8 inch
1 MOA @ 900 Yards = 9 inch
1 MOA @ 1000 Yards = 10 inch
Minute of Angle as it applies to group size and drop:

MOA is used to measure group sizes.
A 1 inch group @ 100 yards is referred to as a 1 MOA group.
A 2 inch group @ 100 yards is a 2 MOA group.
At 100 yards it seems simple enough to understand. However, it can get confusing if you’re not used to the terminology when you move beyond 100 yards.

For example:
A 3 inch group shot at 300 yards is also a 1 MOA group.
A 6 inch group shot at 300 yards is a 2 MOA group.
A 1 ½ inch group shot at 300 yards is a .5 MOA group.
Another way to look at it is like this:
½ MOA @ 700 yards is 3.5 inches
1 MOA @ 700 yards is 7 inches
2 MOA @ 700 yards is 14 inches
3 MOA @ 700 yards is 21 inches
or
3.5 inches @ 700 yards is ½ MOA
7 inches @ 700 yards is 1 MOA
14 inches @ 700 yards is 2 MOA
21 inches @ 700 yards is 3 MOA
Calculations:

How many inches equal 4 MOA at 700 yards?
* (MOA x yards) / 100 = inches
(4 MOA x 700 yards) / 100 = 28 in
*You can drop the last step and make the calculations easier by moving the decimal on the yards two places to the left.
How many inches equal 4 MOA at 700 yards?
(4 MOA x 7.00 yards) = 28 in

How many MOA equal 21 inches at 700 yards?
* (inches / yards)100 = MOA
(21 inches / 700 yards) 100 = 3 MOA
*You can drop the last step and make the calculations easier by moving the decimal on the yards two places to the left.
How many MOA equal 21 inches at 700 yards?
(21 inches / 7.00 yards) = 3 MOA

5 inches = 1 MOA how many yards away is the target?
(Inches x MOA)100 = Yards
(5 inches x 1 MOA) 100 = 500 yards


Minutes of Angle and Rifle Scopes:

Most hunting and target scopes adjust in Minutes of Angle (MOA). The most common adjustment is ¼ or .25 MOA per click. Although not as common, there are scopes that adjust in 1/8, 1/6/, 1/5, 1/3, ½, and 1 MOA.

¼ MOA at 100 yards literally means that each time the scope turret is clicked the bullet impact will move ¼ or .25 inches.

To move the bullet impact 1 inch you would need 4 clicks (.25 x 4 = 1)

Example:

When sighting in a rifle the bullet needs to move up 5 inches to hit the center of target. 5 in / .25 in = 20 clicks or you could think of it like this: need to move 5 inches, 4 clicks per inch, 5in x 4 clicks per in = 20 clicks.

Another application for understanding MOA and scope or sight adjustment is when shooting longer distances. Rifle is sighted in at 100 yards. Your ballistic program tells you that you need to come up 20 MOA to shoot at 600 yards. 20 MOA / .25 = 80 clicks Or 20 MOA x 4 clicks per MOA = 80 Clicks

Boyerracing343 09-08-2011 02:18 AM

thumbs up cane. One more great post from you.

Rarity 09-08-2011 09:56 AM

I have learned plenty much from your post, Canebrake. Thank you~

Zoey,

winds-of-change 09-08-2011 10:36 AM

WOW!!! :confused:

I'll have to read that a few times over.

neilage66 09-08-2011 01:52 PM

I always have to think harder for scope/sight adjustments for ranges under 100 yards/meters.

Ex: How many clicks of a 1/4 minute sight to move POI 5 inches @ 25 yards?

...thinking...

:D

navvet08 09-08-2011 03:23 PM

Thanks Canebrake. I appreciate the lesson; now I believe that I could explain it to someone else.

RogerRonas 09-08-2011 06:21 PM

Understood it all except this part.

35 inches = 1 MOA how many yards away is the target?
(Inches x MOA)100 = Yards
(5 inches x 1 MOA) 100 = 500 yards


Is 35 a typo and should be 5? That would make more sense at 500 yds. Or 35"/1 MOA would be 3500 yards. No?
Great post Cane and I always wondered about MOA, back in the day (30years ago) we always used " to talk about sighting in a rifle.

Roger

canebrake 09-08-2011 07:46 PM

Quote:

Originally Posted by RogerRonas (Post 576949)
Understood it all except this part.

35 inches = 1 MOA how many yards away is the target?
(Inches x MOA)100 = Yards
(5 inches x 1 MOA) 100 = 500 yards


Is 35 a typo and should be 5? That would make more sense at 500 yds. Or 35"/1 MOA would be 3500 yards. No?
Great post Cane and I always wondered about MOA, back in the day (30years ago) we always used " to talk about sighting in a rifle.

Roger

Nice catch Roger, it was a typo.

Correction made, thanks - cane

TCH2FLY 09-09-2011 02:44 AM

Nicely done, but I do have an issue with this:
Quote:

Originally Posted by canebrake (Post 576659)
.... They are units of measurement that happen to be extremely close in value. ....

I know this comes off as nit picky but technically they are not close or even similar. An inch is a linear measurement and MOA is an angular measurement that is actually dimensionless.

An inch (or foot, meter, etc) measures exactly the same amount of distance at all times, a stick measuring one inch is the same length regardless if it is right in front of you or one mile away.
One MOA is an angular measurement that subtends to approximately one inch at 100 yds but as you point out it also subtends to TWO inches at 200 yds, three inches at 300 yds, etc. so it's "value" is always based on distance.

http://i23.photobucket.com/albums/b378/FJ80FUN/moa.jpg


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