What does MOA mean??


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BBsteel
May 8, 2007, 10:24 AM
I pistol and shotgun shoot. I only own a .22 long rifle. Just wondering what is meant by 1/2 MOA, sub MOA, 1 MOA etc... I will purchasing a varmit rifle in the future but not anytime within the next 6 months. The .223 and .308 are both appealing to me and I'll eventually have both so I'll start with the .223.

Thanks for answering

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sansone
May 8, 2007, 10:31 AM
moa= minute of angle. angles are measured in degrees and minutes. 1moa is 1" deflection @ 100yds, the confusing part is 1moa equates to 2"@200yds.

MIL-DOT
May 8, 2007, 10:40 AM
a couple years ago i could have quoted you chapter and verse on all that milliradian,minute-of-angle stuff, but.....:confused:
check out the sniper rifle forums, their FAQ pages will give you the low down in a fairly comprehendable manner. also great sites for the straight scoop on optics.

BBsteel
May 8, 2007, 10:43 AM
That is confusing. Does that mean that 1MOA equates to 3" @ 300 yards? Sounds like you need to establish the yardage when reporting MOA??

Mr White
May 8, 2007, 10:58 AM
Yes. Basically a good rule of thumb is that it is 1" for every hundred yards.

The math:

100 yd=3600"

At 100 yd from target, imagine a huge circle with you at the center and the target out at the edge.

Diameter of said circle is 200 yd which = 7200 inches. circumference is pi*diameter, or 7200*3.1416, or 22619.52 inches.

360 degrees in a circle. 22619.52/360=62.832 inches in 1 degree of that circle. 1 minute=1/60 of a degree, so one minute of that 62.832 inch degree would be 1.047 inches. Pretty close to an inch.

Like I said 1"/100 yds is an estimation. At 600 yd, 1 MOA equals 6.283", not an even 6", but close enough. You can use that math to figure MOA for any distance.

I hope that helped.

Medusa
May 8, 2007, 10:58 AM
MOA means minute of an angle, ie 1/60 degree, roughly it's 1 inch (1.045 more precisely) per each 100 yards, or 29 mm per 100 m. It shows the amount of dispersion of the rifle/ammo system. You can visualize it with the light, the lesser dispersion, the tighter the "beam" is.

Conversion factor is Tan(1/60), or 2.9e-4, or 0.00029. you multiply it with the distance to get the amount of dispersion.

sub moa means that the rifle/ammo combo puts bullets into the circle that is no bigger than 1 inch at 100 yards. All the fractional moas mean the same, for example DSR-1 is a 1/5 moa rifle, with equal ammo it means the group size will be 1/5 inch at 100 yards, basicly a ragged hole.

But be warned, accuracy at long range depends a lot from the ammo, if one rifle/ammo combo shoots 1 moa at 100 yards it doesn't mean it shoots 6 inch group at 600 yards.

For example I shot 10-15cm group at 300 m (330 yards), with Galil Sniper (7.62x51 cal), but at 557 m (610 yards) it was 35-45 cm.

Added: heh mr White, same time replying basicly same thing

BobTheTomato
May 8, 2007, 11:06 AM
I'm not sure if this will help clarify things but in surveying you measure angles in Degrees, minutes, and seconds. So a minute is 1/60 of a degree and a second is 1/60 of a minute. so in other words 30.016666666 degrees is:

30 deg 01 min 00 sec

So if we do the trig for 1 MOA at 100 yds.

Sin 1/60 = x / 100 yds

x = .0290888 yds

x = 1.047 inches at 100 yds

Then 200 yds is 2.094 in and so on


Edit: Oops Medusa and Mr white posted when I was writing

lionking
May 8, 2007, 11:12 AM
quote;sub moa means that the rifle/ammo combo puts bullets into the circle that is no bigger than 1 inch at 100 yards

thanks for breaking it down to simple terms for me.

hate to admit it but I was always confused about this and whenever someone posted "my rifle shoots sub-moa" I never really knew what that meant other than it "sounds accurate".

so lets say if a rifle produces a 2 inch group at 100yds how does that describe it in moa terms?

sectional_density
May 8, 2007, 11:25 AM
"so lets say if a rifle produces a 2 inch group at 100yds how does that describe it in moa terms?"

2 MOA.

Looks like people have already described the calcs pretty well. Another way to consider 1 MOA at 100 yards (1.047") at the tip of a 24" barrel, is that you have about .007" diameter of wiggle room to keep it 1 MOA at 100 yards. A bit harder to do in the field without benches and sandbags. Prone shots w/ bipods are sure nice though!

lionking
May 8, 2007, 11:45 AM
sectional....well duh me.:o I knew I would sound like a dummy asking this but I had to so I could finally understand this.Math was never a good subject for me.

BBsteel
May 8, 2007, 12:14 PM
Great responses, thanks much!! Well understood now.

SnakeEater
May 8, 2007, 01:05 PM
I wish a mod would sticky this thread. This question is asked frequently.

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