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View Full Version : Difference between 4 MOA and 8 MOA?


mikeinla
12-20-2008, 11:26 AM
What is the difference between 4 MOA and 8 MOA???

ps. what is MOA???

Backcountry
12-20-2008, 11:30 AM
Simple arithmetic: 8 - 4 = 4

MOA = minute of angle

elsolo
12-20-2008, 11:32 AM
MOA = Minute Of Angle = 1/60th of a degree

The other answer is one MOA=1" @ 100yds

So that red dot with a 4MOA dot will obscure a 4" circle at 100yds, or 8" at 200 yds, etc.

CSACANNONEER
12-20-2008, 11:36 AM
What is the difference between 4 MOA and 8 MOA???

ps. what is MOA???

4 moa

Math is not that hard.

M. Sage
12-20-2008, 11:37 AM
4MOA isn't too big, depending on what we're talking about. A 4MOA dot in an optic is on the large side, but acceptable depending on what you're using it for. A rifle that can only hold 4MOA... you're getting a bit big with those groups, but it's still pretty acceptable for something like a combat rifle (IIRC, 4MOA is the max allowed by the US military for the M16/M4 and military ammo).

An 8MOA dot in an optic? Huge. Freakishly huge. Unusably huge. You'll cover an entire bullseye at 100 yards. It'll be as big as a human head at 100 yards. A rifle that can only hold 8MOA needs a new barrel, or your loads are using undersize bullets.

nobs11
12-20-2008, 11:44 AM
So I keep hearing this thing about 2MOA, 4MOA sights. A 8 MOA sight will get you 1-2MOA groups out of an accurate gun if you place the dot under the target. It has to do with consistently holding the point of aim in the same place. A blind man can be an accurate shooter if he can hold his rifle the same way for every shot.

How large do you think your iron sights are? They are huge. The cover the black if you put them on the black. Which is why you aim them so that they are under the black.

A lot of shooters use optics to overcome their inability to use sights. Competition pistol shooters are using huge pistol sites to hit little plates at 50 yards. The site covers the entire plate if you hold it so that it obscures the plate.

dchang0
12-20-2008, 11:48 AM
An 8MOA dot in an optic? Huge. Freakishly huge. Unusably huge. You'll cover an entire bullseye at 100 yards. It'll be as big as a human head at 100 yards.

What's funny is that most C-More Railway sights come with an 8MOA dot module installed. It's practically a given that you'll have to order a $50 replacement, either 2MOA or 4MOA.

Still, 8MOA is perfect for CQB/home defense, so I guess it ain't all bad. And nobs11's right--the C-More sights are most often used by pistol competitors.

M. Sage
12-20-2008, 11:53 AM
How large do you think your iron sights are? They are huge. The cover the black if you put them on the black. Which is why you aim them so that they are under the black.

Depends on the gun. On a Socom II, the front sight seemed to cover an 8" target at only 50 yards (16MOA!?), one of the reasons I don't really like that rifle. On my Garand with the NM sights, it's probably only covering about 4MOA or so. My AK front sight is surprisingly similar in width. A standard-width front post might cover 6-8MOA by my guess.

The reason you need a wider front sight than a wider dot in optics is because it's harder to pick the sight up and see it against the target. It doesn't exactly have a brightness adjustment on it. :p When it gets dark, it can be pretty hard to see a really narrow little front sight; harder than seeing a big fat one, anyway.

As far as handgun sights, wider/chunkier sights help with picking up the sights and aligning them faster. My CZ-52 is nowhere near as good at putting aimed shots downrange quickly as my Sig with its big dot XS sights, but it doesn't even feel hard to shoot targets at 25 yards with the teeny, narrow little Czech sights.

What's funny is that most C-More Railway sights come with an 8MOA dot module installed. It's practically a given that you'll have to order a $50 replacement, either 2MOA or 4MOA.

Still, 8MOA is perfect for CQB/home defense, so I guess it ain't all bad. And nobs11's right--the C-More sights are most often used by pistol competitors.

I don't know about "perfect"... I've had no problem picking up 1MOA or 4MOA dots on my old EOTech and Aimpoint respectively for quick action.

Handguns... Pff, they're not even going to hold 8MOA anyway. :p

Darklyte27
12-20-2008, 1:10 PM
if your rifle shoots 1 MOA at 100 yards, that means it can keep shooting in the same 1 inch circle. 2 inch circle at 200 yrds so on.

others can better explain how the minute of arc works than i could.

aplinker
12-20-2008, 1:12 PM
MOA = minute of angle.

Around you is a circle of 360 degrees. Each degree has 60 minutes. So, an MOA is the pie piece starting at you that's 1/60th of a degree. It's useful because it's a consistent measurement for increasing distance. For example, at 100yds 1MOA is approximately 1". At 200yds it would be 2". 1000yds would be 10", and so on.

The idea that dot size corresponds to maximum accuracy is ridiculous. You just center the dot. It's not that complicated.

tommyid1
12-20-2008, 5:11 PM
4 inches at 100 yards, 8 at 200

NeoWeird
12-20-2008, 5:50 PM
Let me try and better explain it than has already been said.

See in firearm shooting, when talking about accuracy, group size is NOT an indication of an accurate rifle. You might be thinking that if a rifle can shoot in the same area repeatidly it means that it's an accurate gun. While that is somewhat true, it is not an absolute test of an accurate setup. You could take a .22 rifle and put the target a half inch away from the muzzle, and outside of muzzle blast ripping up the target, the group size will be nearly the size of the bullet.

Does that mean that this particular rifle is accurate? Not exactly. Now you could take a different rifle and put the target out to 200 yards, something that starts to get very challenging for a .22 LR firearm, and get a 3" group.

Now which firearm is more accurate? Based on these two targets alone a new shooter may jump to the conclusion that the smaller group rifle has MUCH better accuracy, but they aren't factoring in all the elements to accurate shooting, primarly distance. There are other factors also, such as ammo used, barrel length, twist rate, enviornmental conditions/weather, etc etc etc.

Both targets had bullets that had the same origin, the muzzle, but they spread out as they traveled farther from the muzzle. This creates a cone type of shape that is directly in the potential path of a bullet that leaves that gun. If you've ever tried to use a laser bore sighter to set your target and then shoot the gun with the same point of aim, you will notice that you will rarely hit where the laser pointed, especially at greater distances. This is because of this cone effect.

So, now, imagine that you are holding your rifle and you're standing on the center of a giant dial clock. You're looking straight up at the 12 with the 6 directly behind you. Around you are the 60 minutes or seconds depending on the notches you are looking at. Each of those notches gets divided again 6 times to create the 360 degrees of a circle.

Now here is a question to ask yourself - how much space is between two of those notches? You don't know. Because if the circle is 2 inches in diameter or 2 miles in diameter the distance between them will be greatly different. This goes back to those targets I mentioned before. Group size does not tell you how accurate a gun is, only a visual represetnation of what the cone size is at a particular distance.

So back to the clock. Between each of those notches is a degree. Let's focus on only one - the degree that starts at the 12 (or zero degree) and ends at the degree next to it (or one degree). You look through your scope and the bordering notches are at each side of your field of view. You zoom in with your scope and you see that within this degree it is further divided into 60 smaller pieces. Each of these pieces is a Minute of Angle, or MOA (each minute can get divdided again into 60 seconds but that's far too precise for most shooting). If you ever took higher math in school you might have had a teacher that would yell at you if you said something like 50.6 degrees when doing Trig. That's because that .6 degree is actually 36 minutes of angle, so the proper way to say it is "50 degrees 36 minutes".

So back to the clock, you are looking down the zoomed rifle and you can see the divided degree and see each numbered minute of angle. You pick a random minute, let's say the 13, and you shoot at it until your are out of ammunition. You walk down range and see that even though you were aiming at the 13, some of the bullet holes cover the entire width of the 12 and the 14. That's because this cone, even though centered on the 13, had the potential to hit on either side of the 13. So your rifle shoots 3 minutes of angle, or 3 moa. Were you to place the target back farther, the bullets would still, theoretically, travel along this same path and consistnatly group on these same minutes until bullet drop off got to the point where it could reach them anymore. So your rifle is ONLY 3 MOA accurate and that's it - doesn't matter how far or near, it will always be 3 MOA. The sub MOA that some companies promise means that if you aim at the 13 with their rifle, it may hit either side but it will always hit the 13. So even though it may not hit EXACTLY where you are aiming, it WILL hit the target every time (assuming you do your part).

Now since this is a cone, it is 3 MOA in ALL directions. So 3 MOA up, 3 MOA to either side, 3 MOA to the top right, etc. As said, this influences targets. A mansized target at 100 yards may take up 10+ MOA, but at 1,000 yards he may only take up only 3 seconds of angle - obviously this will be a VERY hard target to hit seeing as how he only takes up a VERY small portion of your cone of theoretical bullet path.

As said above, this also effects optics. The optics cover a portion of your field of view, and so red dots especially tell you how big it is. If you are using a rifle that can shoot 1 MOA groups and you going to be shooting at a 2 MOA target, you won't want an 8 MOA red dot to be covering everything, other wise you couldn't see what you're aiming at. It's always a good idea to use a reticle with an MOA smaller than the MOA of your target so you can still see what you're aiming at. If you are shooting so far that the reticle HAS to cover the target, it's a good idea to learn how to use your scope outside of just a point-click interface.

If you followed that you will either understand MOA better now or be so ****ed up confused that no amount of explaination will undue the damage I just did. Either way, you'r welcome. :D

ar15barrels
12-20-2008, 8:42 PM
Most people round MOA to 1" at 100yds, but it's actually 1.047" at 100 yds.
This does not seem like much, but when you are correcting 38 MOA to get on target at 1000yds, that adds up to an error of almost 2" which will throw you out of the X ring and into the 10 ring.
Also, 1 MOA at 1000 yds is 10.47".

rksimple
12-20-2008, 8:50 PM
Most people round MOA to 1" at 100yds, but it's actually 1.047" at 100 yds.
This does not seem like much, but when you are correcting 38 MOA to get on target at 1000yds, that adds up to an error of almost 2" which will throw you out of the X ring and into the 10 ring.


Actually, at 1000 yards, its .47 inches per MOA adjustment. It adds up to 17+ inches at 1k discrepancy.

ar15barrels
12-20-2008, 8:54 PM
Actually, at 1000 yards, its .47 inches per MOA adjustment. It adds up to 17+ inches at 1k discrepancy.

Good point.

You up for Coalinga next weekend?
I put the IOR on my 50 today and loaded up some plinking ammo.
Also went through the trigger so it's ready to lob some lead.

rksimple
12-20-2008, 9:40 PM
Good point.

You up for Coalinga next weekend?
I put the IOR on my 50 today and loaded up some plinking ammo.
Also went through the trigger so it's ready to lob some lead.

Maybe so. We'll talk on the 24th. I'll swing by your place.

I need to load 308. I'm down to 30 rounds!

ar15barrels
12-20-2008, 10:07 PM
I need to load 308. I'm down to 30 rounds!

So do I.
I have over 30 rounds of BMG loaded though.

Going to zero it at Angeles tomorrow.

workinwifdakids
12-20-2008, 11:56 PM
Bad for attracting shooters and 2A activists:
Math is not that hard.
:censored:

Good for attracting shooters and 2A activists:
See in firearm shooting, when talking about accuracy, group size is NOT an indication of an accurate rifle. You might be thinking that if a rifle can shoot in the same area repeatidly it means that it's an accurate gun. While that is somewhat true, it is not an absolute test of an accurate setup. You could take a .22 rifle and put the target a half inch away from the muzzle, and outside of muzzle blast ripping up the target, the group size will be nearly the size of the bullet.

Does that mean that this particular rifle is accurate? Not exactly. Now you could take a different rifle and...

evollep3
12-21-2008, 1:06 AM
some good info here!
here is a question for everone its kind of in the topic so in everyone's recommendation what would one look at if they want their optical to be set around 200 yards or more what features would you guys look for?

deldgeetar
12-21-2008, 2:02 AM
The difference between a Saiga @ 100 yards and a Mini-14 @ 100 yards.:29:

sb_pete
12-21-2008, 4:00 AM
some good info here!
here is a question for everone its kind of in the topic so in everyone's recommendation what would one look at if they want their optical to be set around 200 yards or more what features would you guys look for?

Not quite sure what that meant, but you should start a new topic for that question.

Nice explanation Neo, I may steal some of that from you next time somebody asks me ;).
-Pete

Fjold
12-21-2008, 9:36 AM
some good info here!
here is a question for everone its kind of in the topic so in everyone's recommendation what would one look at if they want their optical to be set around 200 yards or more what features would you guys look for?

It depends on what you want to do with it. To hit a man sized target at 200 yards the 8 MOA dot would work, just hold center of mass. To me, a 2 MOA dot is huge. One of my long range varmint scopes has a 1/8 MOA dot and that has worked well for me out to 600 yards on ground squirrels and prairie dogs.

SilentScream
12-22-2008, 12:14 AM
Let me try and better explain it than has already been said.

See in firearm shooting, when talking about accuracy, group size is NOT an indication of an accurate rifle....

Actually MOA is a great way of comparing rifle accuracy, the problem is itís very hard to make an exact angle measurement two inches from the muzzle but 100 yards is a lot easier and 1000 yards is the best, but at that distance (1000yards) atmospheric factors start to take effect and might not be consistent from shot to shot, thus will not represent true accuracy of the gun.

Remember MOA is an angle and angle value does not change with distance.

ar15barrels
12-22-2008, 8:59 AM
Remember MOA is an angle and angle value does not change with distance.

Tell that to a 1K shooter... :D