Still having trouble understanding MOA

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Kimio, just go out and shoot. Learn the fundamentals and practice; the math will take care of itself. The math will get you close, but skill will make the hits.
True marksmanship IMO is being able to adjust and get hits in the field when all you have are your two eyeballs and experience.
 
MOA definition has been covered.

Accuracy defined by MOA. I think this should be covered a bit. Often you here someone say, I have a 1 MOA rifle. This means it shoots ~1" at 100 yards. For a perfect shooter, it should shoot 10" groups at 1000 yards. It won't, but at 200, it should be close to 2" and 300 close to 3". These are really just goals. If your 1" rifle at 100 shoots 2.5 - 3" at 200 and 4 - 6" at 300, you are doing pretty good.

Long range drop/wind estimation. . . you need adrop chart for your load. Here is the best website to make it from. JBM Ballistics
 
Both the mil and minute of angle has oft times been confusing in the shooting sports.

A century or so ago, one minute of angle was established as exactly 1 inch at 100 yards for the shooting sports in the USA. Target scoring rings were spaced in exact inches. And USA made sights back then were so calibrated but have changed a bit in the last decade or two. In Europe, a metric system's used.

There are four standards on this planet for what a mil is. Check it out on wikipedia; quite interesting.
 
you can learn range finding aprox by triangulation and a mil dot scope. and a little math . the way i was taught was using say a house door on average is 3 feet wideso in the distance you compair it to the mil dot spacing and turn that unto a decible and multiply that with ur balistics data to adjust ur dope..but that still is aprox some doors are 29 inch some 36 wide ect
 
Whats the 4th Mil.

There is actualy is 6283 mils in a circle. since that's not divisilbe inot fractions which are whole numbers the artillary mil was adopted which is 1/6400 of a circle. The infantry mil is 1/6280.

The artillary mill is 3' 22.5". or 3.375

The real mill 1/6283 is 1/17.7278 of a degree (60 min. times 17.7278 X 360 =6383.008

Now you can see why they chose the artillery mil of 1/6400, its all too confusing.

All you really need to know is the angle is substanded by 1 unit at a distance of 1000 units. 1 yard at 1000 yard, 1 meter at 1000 meters etc.

So using mils we can determine range.

The target size in yards (or meters) times 1000 divided by the number of mils covering the target = range to the target.

Lets say your target is 18 inches high. 18 inches is 1/2 yard so .5 X 1000 = 500. Lets say looking through the scope your target is two mil dots high, So 2 X 500 = 1000 yards. If the target is 1/2 of a mil in the scope it would be 500 X .5 or 250 yards. (If using meters simply replace the yards by meters.

For all practical purposed you can forget the 6400, 6380 or 6383.008 for ranging purposes.

And if your ranging in mils and have MOA adjustments use 3.375 minutes per mil. Or if you figure you need to come up one mil, you would come up 3.375 inches.

You can use a computer and get the decmal place to the nith degree but you'll never know down range. By the time you get all the math figured out, the target will die of old age.

Remember KISS whether its Mils or MOA. Sure 1 MOA is 1.047 and not 1, but can you tell the difference shooting in the wind at 1000 yards. Same with mils, I doubt any of us can tell the difference between 6383 and 6400 at 1000 yards. You'd be better off concentrating on your marksmanship fundamentals and learning wind, which will get you first.
 
kraigwy asks:
Whats the 4th Mil.
Click to expand...
There are 2000 X pi milliradians (≈ 6283.185 mrad) in a circle. So a milliradian is just under 1⁄6283 of a circle, or ≈ 3.438 minutes of arc. Each of the definitions of the angular mil are similar to that value but are easier to divide into many parts.

1⁄6400 of a circle in NATO countries.

1⁄6283 The “real” trigonometric unit of angular measurement of a circle in use by telescopic sight manufacturers using (stadiametric) rangefinding in reticles.

1⁄6000 of a circle in the former Soviet Union and Finland (Finland phasing out the standard in favour of the NATO standard).

1⁄6300 of a circle in Sweden. The Swedish term for this is streck, literally "line". Sweden has not been part of NATO nor the Warsaw Pact. Note however that Sweden has changed its map grid systems and angular measurement to those used by NATO, so the "streck" measurement is obsolete.
 
Wow!!! There is a reason I chose to teach English and history instead of math and science. I think all this math is going to make my head explode :eek:

Truly, though, I am glad there are so many folks on this forum who are able to explain the details when someone asks a question like this. This has been truly informative :)
 
The OP was confused about a couple different things, but I didn't seen this correction in the thread.

The simplest one is how manufacturers or shooters define their gun's accuracy. In that case, it it not about changing POA, scopes or anything. They define MOA with how consistently accurate the gun will be if NOTHING changes....for a given range, with match grade ammo.

eg. If you could freeze a rifle from moving at all, shot it 3-5 times with good ammo at 100 yards, most guns will not shoot bullets all through the exact same hole. The difference between the holes in that group defines the inherent MOA accuracy of the gun.
 
robertsig's good comment:
If you could freeze a rifle from moving at all, shot it 3-5 times with good ammo at 100 yards, most guns will not shoot bullets all through the exact same hole. The difference between the holes in that group defines the inherent MOA accuracy of the gun.
Click to expand...
Note the size of the group also reflects the accuracy of the ammunition. Bullets more consistant in weight, balance and shape fired from cases with the same uniformity using primers and powder charges also with the same uniformity will shoot the smallest groups.

But small variables still exist in each of the components. Nobody's put a firearm and ammunition together that, when tested in a machine rest, puts all the bullets in exactly the same hole....a zero MOA group.
 
Estimating distance requires practice. It helps to know the normal distances between everyday objects you see. For example, wooden electric/telephone poles are commonly placed 320 to 340 feet apart. So when you see a line of power poles along the roadway you can equate them to be about 110 yards apart. To me this is easier than trying to visualize a football field since a football field is void of anything of common sizes such as trees or cars to judge distance by.
 
I'm confused...
Click to expand...

That's OK, it gets better.

As to the one hole group:

Dr. Franklin W. Mann dedicated his life trying to get the one hole group (See. "The Bullet's Flight, from Powder to Target).

Mann developed the Mann Accuracy device to test ammunition which the military still uses today.

In 1985 Lake City Ammunition Plant's production of 5.56 ammo was failing to meet the standards set by the army. LC blamed their Mann device.

Robery L. McCoy did a series of test of LC's ammo with their Mann device. They used 4 different Mann's and tested M855 & SS109 ball and M856 & L110 tracers, With a control, carefully loaded test round (52 Gr SMK, Remington Brass, 25 grs of 3031 and CCI450 primers).

This was a long extensive test but the Reader's Digest Version is they found nothing wrong with LCs Mann Accuracy Devices but the bullet seating of Lake Cities manufacturing.

When you get all your components the same, two other factors come in to play. That being the bullet seating and heat. It's near impossible to get two bullets seated in the case the same way each time and keep the barrel/ammunition at the same temperature each and every time.

We know that to get accuracy the bullet has to enter the barrel exactly the same each time, which means it has to be seated in the neck of the case perfectly and consistently. You can narrow your chances of error by using competition seating dies but even then you can't make it perfect.

(This was Lake City's problem, not the Mann's)

The second problem was temperature. We know that the higher the temperature, the higher the pressure, and velocity. The problem is getting the temperature the same from shot to shot. The barrel heats up so putting the loaded shell in the chamber from shot to shot gives you a temperature change. If you wait until the barrel/chamber cools, the out side temps changes.

The Mann device consist of a heavy match barrel action set in a metal V trough, after recoil the device falls back into the same pace for the next shot. Any time you have that much mass (as in the Mann's cradle) the mass is going to expand and contract giving you a different point of impact. The rifle, regardless of the steady hold, is going to do the same thing.

Like I said, this is a brief, condensed version of McCoy's report but it shows that you'll never get a "one hole group" even in laboratory settings. Shooting in a vacuum wont keep heat from entering the equation.

What this has to do with MOA/Mil Dots, etc,? Not much except to say what we should strive for is not the One Hole Group, but for Practical Accuracy. Practical Accuracy may be different for hunting vs. Bench Rest Shooting.

The critical asspect of accurate shooting is not the rifle or ammo but the shooter. You see it all the time on the internet. Itty Bitty sub minute groups fired from sandbagged, benched rifles.....but in reality you find very few "cleaned" targets at 1000 yards. Not because the rifle/ammo combination can't do it, its because the shooter can't do it.

Think about it, the X-10 ring on the 1000 yard HP target is 2 MOA (20 inches). Why can't these 1/4-1/2 MOA rifles clean the target? A 2 MOA rifle is capable.

When it comes down to the rubber meeting the road, or bullet meeting the target its all about MARKSMANSHIP FUNDAMENTALS. We the shooter are the weak link in the chain.
 
"Ok so the way it was explained to me is that MoA (minute of angle) is essentially the distance in which the round begins its downward descent due to gravity. " :confused::confused:


I strongly suggest that you do not listen to what this person tells you. What a bunch of baloney!!
 
"turn that unto a decible"

Oh boy, in addition to worrying about gravity, we now need to learn about acoustics to shoot accurately??? :confused::confused:

I hope you meant "decimal". A decibel is obviously 1/10 of a Bel ( as in Alexander Graham Bell); often used in acoustics. But you already knew that.
 
DaveP is 100% correct;

MOA is nothing but a unit of measurement. A measurement that is subtended, meaning it changes as distance increases, but constant changes.

Forgetting that a MOA is 1.043 and using 1". It would be 1" at 100 yards, 2" at 200, 3 at 300, etc etc.

As to drop of the bullet, it can be used to measure that drop down range, or the movement laterally caused by wind, or up movement by changing your sights (which angles the barrel up).

Scopes and iron sights are set to give you a certain movement with each click. It may be 1/4 MOA, 1/2, or 1 MOA.

BUT THAT IS A GUIDELINE and regardless of the quality of scope, it may not always be true.

Best way to check your scope "clicks" is to set out a 6 ft paper target. Take a plumb bob and hang it from the center of the top of the target. Draw a line straight down following the string. Now place a target or some other aiming point at the bottom of the target. Sight in on that point. Then count 10 clicks, shoot again using the bottom aiming point. Do this again, coming up 10 more clicks, shoot another group. Keep doing this until you reached the top of the paper. Now measure the distance between each shot group.

That will give you an ideal of what each click really means, and it also tells you if the clicks are constant moving up in elevation.

Record the differences in your rifle's data book which will allow you a more accurate adjustment when moving to extended ranges.
 
Oh boy, in addition to worrying about gravity, we now need to learn about acoustics to shoot accurately???
Click to expand...

Well, if you aren't using proper ear protection, the ringing in your ears could be a distraction on the next shot... :rolleyes:
 
Kraigwy's excellent comments:
The critical asspect of accurate shooting is not the rifle or ammo but the shooter. You see it all the time on the internet. Itty Bitty sub minute groups fired from sandbagged, benched rifles.....but in reality you find very few "cleaned" targets at 1000 yards. Not because the rifle/ammo combination can't do it, its because the shooter can't do it. Think about it, the X-10 ring on the 1000 yard HP target is 2 MOA (20 inches).

Why can't these 1/4-1/2 MOA rifles clean the target? A 2 MOA rifle is capable.
Click to expand...
To elaborate a bit.......

Those 1000 yard matches are fired in the prone position slung up with a rifle. The best prone competitors can hold their aiming point inside a 5/8 to 3/4 MOA area with both scope and aperture sights. They will try to break their shots inside a 1/2 MOA area without jerking the aiming point around. The best of these rifles will shoot inside 6 inches all day long, same as the best of the 1000 yard benchrest rifles.

As no human can reposition their shoulder fired rifle exactly the same way for each shot, the rifle's recoil will move its bore axis a tiny bit different for each shot as the bullet goes down the barrel adding about 1/4 MOA to where all the bullets will go. And between shots, they check the motion of heat waves through their spotting scope as an indicator of how the wind's changed, then make a sight adjustment; if they don't make errors more than 1/4 MOA doping the wind, they're one in a million. So this adds another 1/4 to 1/2 MOA horizontally to the group. After all's said and done, the best scores end up with 99% of their 20 record shots inside that 20 inch, two MOA, 10 ring. Inside the 20 inch 10 ring's a ten inch X ring used to break ties when the numerical scores are the same.

Once in a while someone will shoot a perfect score, but not often. I've shot a few hundred 1000 yard matches and only fired 6 perfect scores. Once with a 7.62 NATO Garand, twice with a .308 Win. bolt gun using aperture sights, twice with .30 caliber magnums with a scope and once with a .264 Win. Mag. with aperture sights.
 
"meaning it changes as distance increases, but constant changes"

I find it easier to visualize it.

Look at a ball diamond. Stand on home plate. The two foul lines form an angle at home plate. It's not minute of angle, but it's still a fixed angle.

As you walk to the pitcher's mound from home plate the distance between the foul lines increases. Keep walking to second base and the distance between the foul lines has increased even more. When you get into deep center field they're really far apart.

Minute of angle is just a smaller angle, but the farther out you go the wider it gets between the two lines forming the angle.

Of course MOA is not a two dimensional angle, it's really a horizontal cone.

John
 
I love math twice as much as the next guy, but all these different conventions and approximations for mils and moa seem really unnecessary. If you use mils in their true (read: trigonometric) form, 1 mil = 1 milliradian, or (1/1000)*radius of the circle. Distance to the target will be the radius of the circle.

Using basic math, radius = (target size/# of mils)*mils per radius.

There's no need for all the 1/6400 1/6283 1/6300 nonsense, as long as you express the mil in terms of the radius the units all come out in the wash :p don't worry about all the mumbo jumbo. Using kraigwy's earlier example, (.5 yards/2 mils)*1000 mils = 250 yards.

Similarly, if you want to know your adjustment, (radius/mils per radius)*mils per click = adjustment per click.
 
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