Trying to understand MOA and how it translates to my AR irons.

K

Kimio

New member
Ok, I'm trying to make sense of how MOA works. Other topics I've searched and read really have not given me the answer I'm looking for.

If I understand it correctly MOA stands for Minute of Arc, and will determine my accuracy and general groupings at various distances.

If I recall correctly, if I have a rifle that can shoot 1 MOA then at 100 yards my groupings should be within 1 inch, for every 100 yards after it will then increase by one inch intervals, 200yrds = 2", 300yrds = 3" etc.

Now, I'm shooting my AR15 with the A2 style carry handle irons. The knob on that allows the adjustment for elevation always confused me a bit, so I've really not tried fiddling with it too much (I don't own a spotting scope either, so it makes it difficult to see what my groupings are at 100yrds, and anything beyond that at my range is steel target plates)

Written on a flat part of the knob and without any adjustments to it, is 6/3, what exactly does this mean? Also, what confuses me is I don't understand how much of an adjustment each "click" or one notch movement changes the elevation. I started out using a Mosin Nagant which had it's elevation adjustments set in 50 meter intervals from what I was able to discern from it. So how exactly do I figure out how to adjust for elevation with my rear sight to keep it shooting with MOA standards (I don't know how to exactly explain this, someone tried to explain this to me before, but never really answered my question on how to adjust my irons for elevation and how much each "click" adjust my "MOA")

Can someone please explain this to me? It's been bothering me for some time really.

Rifle Specs: Full Length AR15 with 20" barrel using standard A2 carry handle sights with a 1/9 twist rate.
 
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A quick Google search turned up this. Didn't watch the whole thing, but what I did seemed correct.

http://www.youtube.com/watch?v=j5QCGWYfHWk

On edit, Generally A2 sights are half-minute, so one click would change point of impact by 1/2" at 100 yards. Some match sights are 1/4 minute, but you would probably know if yours are 1/4 minute, as you would have paid more for it.
 
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The numbers 6/3 are elevation changes. In other words "3" would be used and 300 yards, and so on. If your rifle is sighted in at 300 yards, but you need to shoot at 500 yards, you would dial in the "5" which should put you in the ballpark.

You need to find your rifles literature on the sights and they will tell you how much each "click" on the front or rear sight will change the elevation or windage at 100 yards.

Some rifles front sights may move the point of impact 1" at 100 yards, while other may move it 1 1/2", etc.

Same with the rear sights. Some may move the POI 1/2", or 3/4" or even 1 1/2".

MOA means minute of angle, which is really 1.0472" at 100 yards, but most people round it off to be 1" at 100 yards, 2" at 200 yards, etc. But just remember, that little bit you are rounding off comes into play when you are shooting really long distances.
 
Thank you both, that really helped. Most of my shots are out to 300 yards anyway, anything beyond that is usually too hard to see at my range with regular irons.
 
Steve has it pretty well on, IMO. To add to it, where "minute of angle" comes in - a circle has 360 Degrees to it, and between each degree, there are 60 Minutes (IIRC).
When you shoot a weapon, it's bullet travels not-always-straight, but varying in some angle from the bore-line of the gun. If we have the muzzle as the center-point of an angle, and form a cone outwards from that point, 1 MOA is approximately a 1" width at 100 yards from the muzzle of that rifle. Or, the cone will be 0" wide at the muzzle (center point), and approx 1" wide at 100 yards. 200 yards is 2", 300 yards is 3", so on and so forth.

Scope designers often use 1/4" @ 100 yards (thus 1/4MOA) per click. Thus, out of the 1 minute, the point of impact (or that tiny crosshair center point), will be shifting 1/4 of a minute per click of elevation (up/down), or windage (left/right).

High-end sniper-scopes will use 1/8 MOA for better precision, but this involves A LOT more work in manufacturing the scope (hence the higher cost), and most hunters don't need to be adjusting their POI at 1/8" increments.

Attached image could clarify...
MOApicture.jpg


As for the Mosins - they're measured in "Arshins" which are a really odd-ball Russian measurement system that bears a little resemblance to metric, and has the same purpose-of-construction as our own messed up Inches/Feet/Miles etc (which, with all respect, is flat confusing and harder to learn (for me) than the wonderful metric system. :P)
 
From the manual

Rear sight elevation adjust for proper target distance as long as the target was properly zeroed.

Elevation correction is one click = 1/4 (0.7 cm) at 82 feet (25 m) or 1 inch (2.8 cm) at 328 ft (100 m).

Properly zeroed means 25 m zero target at 25 m with the rear sight adjusted all the way down to 6/3. When zeroed at this distance, you are zeroed at 300 m also. Then the numbers on the side will adjust the rifle to proper target distance eg. 5 for 500 meters.
 
Also keep in mind that unless you have a same-plane aperture, the large aperture will have a different zero than the small aperture. Your manual should cover that and explain the sight adjustments (which are in meters, not yards)
 
As for the Mosins - they're measured in "Arshins" which are a really odd-ball Russian measurement system that bears a little resemblance to metric, and has the same purpose-of-construction as our own messed up Inches/Feet/Miles etc (which, with all respect, is flat confusing and harder to learn (for me) than the wonderful metric system.
Click to expand...

Actually, the measurements used on the Mosins are not really metric per se.

The Russians used Paces, or the average measurement of the individual soldier's foot steps. Don't really remember for sure now but I think it was 30 inches. So the 100 mark would be 100 paces, 200 = 200 paces, etc etc,

Regardless, I modified mine where it shoots on at 100 yards with set at the 100 pace mark and its right on at 200 yards when set at 200 paces, 300 at 300 etc.

As to the OPs question. The A2 sights have marks for what one would acutally shoot. 3/6 meaning 300 yeards and flip up the sight 600 yards.

The sights are basicly how you shoot. My White Oak upper, has sights marked at 2 meaning 200 yards and 300, 400, to 600, At 1000 you use your 600 yards sight setting and turn the front post down 4 full revolutions to get you on at 1000.

The army dosn't use inches any more, The clicks on the M16 are .7 CM.

A MOA is acutally 1.043 inches, but for all practical purposes use 1 inch. I can't shoot good enough to see the .043 inches and I doubt there are many out there that can.

If the sights still confuse you PM me with your e-mail address and I'll send you the M16 manual in .pdf format that will show you how to work your sights.
 
1/8 MOA adjustments are also valuable for long range accuracy, not just precision at closer range. Remember, on a scope with 1/4 MOA adjustments, the smallest adjustment you can make at 1000 yards is 2-1/2"...
 
As for the Mosins - they're measured in "Arshins" which are a really odd-ball Russian measurement system that bears a little resemblance to metric, and has the same purpose-of-construction as our own messed up Inches/Feet/Miles etc (which, with all respect, is flat confusing and harder to learn (for me) than the wonderful metric system.
Click to expand...

Actually, the measurements used on the Mosins are not really metric per se.
The Russians used Paces, or the average measurement of the individual soldier's foot steps. Don't really remember for sure now but I think it was 30 inches. So the 100 mark would be 100 paces, 200 = 200 paces, etc etc,
Click to expand...

While you are both correct about arshins, all Mosins manufactured after the Soviets took over have metric sights.
 
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