Formula for MOA?

[Scratchthejeepguy]

I'd like to know how my rifle is shooting, but I'm shooting at odd distances right now.

My smallest group was a 5 shot group at 1.142 inches (outside to outside, but calipers zerod on bullet)
And shooting at 182 yards.

My average group was 1.353 (6 groups)

How do I figure out if I'm shooting 1MOA, 2MOA etc...



Also is a five shot group what most shooters call a "group" or is it different?

 

[thrusty]

+1 on what DFOOSKING said...
To put it into words....MOA is relative to your distance (in yards).

The numbers:
1MOA @ 100yrds = 1.047"
1MOA @ 200yrds = 1.047" x 2 = 2.094"
1MOA @ 300yrds = 1.047" x 3 = 3.141"
etc...etc...etc...

Your Example:
1MOA @ 182yrds = 1.047" x 1.82 = 1.905".....Thus, a group smaller than 1.905" at 182yards is SUB-MOA.

Edit: Sorry, missed your second question. Most of us will use a 3-shot or 5-shot group depending on what we're trying to accomplish. Generally speaking, a 5-shot group will yield you better data...however, I wouldn't bet my life on a single 5-shot group. If you continue to get the same results, 5-shot group after 5-shot group...and even a 10-shot group here or there....then yes, you can reasonable say that the gun and your ammo is damn accurate. Regardless, your 5-shot group at 182yrds is nice work.

 

[Scratchthejeepguy]

Thanks guys, I knew there was a simple formula.

... math rears its ugly head once again....

So let me get this straight...

A 182 yards, I take that distance (1.82) times 1.047 equals 1.905.

Then take my group size of 1.142 divided by 1.905 equals, my rifle shot .59 MOA in that group.
And with an average over 6 groups of 1.353, I averaged .710 MOA...?

I'm pretty happy with that for my stock SPS tactical then!

 

[proneshooter]

The complete formula is MOA @ X yards = object diameter in inches x 95.5 / distance in yards

The object could be whatever: shot group, scoring ring, etc.

 

[M40_A1]

I just committed 1.047 to memory.

Range is in hundreds of yards. (If you're a metric $#%%^, then you're on your own)
Then remember that if you divide by the range, you also divide by 1.047.
And if you multiply by the range, you also multiply by 1.047.


So, a 3.6" group at 735 yards would be:

3.6 / 7.35 / 1.047 = .46MOA

------------------

Or, 3MOA at 750 yards would be:

3 x 7.5 x 1.047 = 23.6"

3-shot groups don't tell much unless your stick is a consistent tack driver. 5-shot groups tell more, and 10-shot groups (the military testing way) tells even more. The nice thing about 3-shot groups is that just about anyone can shoot enough to just pick and show their one hole groups!

 

[longun83]

I'd like to know how my rifle is shooting, but I'm shooting at odd distances right now.

My smallest group was a 5 shot group at 1.142 inches (outside to outside, but calipers zerod on bullet)
And shooting at 182 yards.

My average group was 1.353 (6 groups)

How do I figure out if I'm shooting 1MOA, 2MOA etc...



Also is a five shot group what most shooters call a "group" or is it different?

I'm new to the math as well, but I think whatever you measure with your calipers you then subtract the calibre size from that.

1.353 - 0.308 for example

 

[proneshooter]

I'm new to the math as well, but I think whatever you measure with your calipers you then subtract the calibre size from that.

1.353 - 0.308 for example

Correct, subtracting one caliber from the max spread between bullet holes normalizes group size to center to center distances.

 

[ksthomas]

Long version, but it'll give you the accurate MOA measurement for any distance. A Minute of Angle is 1/60th of a degree, and there are 360 degrees in a complete circle. The circumference of a circle is 2xPi, or 2x3.1416x the radius. So for any range, R, one MOA equals 6.2832xR/= .00029089xR.

If your R is 100 yards (3,600"), one MOA will be 3,600x.00029089 = 1.047".

So,
@ 150 yards we have 5,400", so 5,400x.00029089 = 1.570"
@ 175 yards we have 6,300", so 6,300x.00029089 = 1.833"
@ 219 yards we have 7,884", so 7,884x.00029089 = 2.293" etc., etc..

 

[Scratchthejeepguy]

I'm new to the math as well, but I think whatever you measure with your calipers you then subtract the calibre size from that.

1.353 - 0.308 for example

Yeah, I just stick a bullet in my calipers, then zero it. Then measure the outside of the group. It deducts the caliber size for me.

 

[Scratchthejeepguy]

3.6 / 7.35 / 1.047 = .46MOA
Grouping/yardage/1.047= MOA

I like this formula best!