Still having trouble understanding MOA

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Kimio

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I don't know why I am having this problem.

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. A 1 MOA rifle should shoot one inch groups at 100 yards and for every 100 yards afterwards it should increase by 1 inch increments so 200yd = 2", 300yd =3" etc.

I was never good at math so how do you judge this in a scope? My uncle tried to explain this to me over the phone and it just wasn't taking very well.

He said that essentially you adjust the elevation an windage knobs in accordance to the distance and size of the target. So let's say you have a six foot man at 300yds you would then adjust for that distance and if you know you have a 1 MOA rifle you'll have to adjust for that increased size in grouping.

Problem is, how do you know the target is 300yd away how do you adjust for drop, is it done with only the windage/elevation knobsi? Ive unfortunately had extremely little time with any sort of optics, from what I can tell some if not many rifles have milidots or built in range finders but when it was explained to me how they are functioned it went way over my head.


Can someone please explain this to me
 
The only way to know the distance to the target is to measure or guess. You're never going to guess right without LOTS of training and practice.

You are quite correct. MOA is approximately one inch at 100 yards. (Technically 1.0471996 inches but the .0471996 is typically ignored for obvious reasons. ;))

The knobs on your scope adjust the bullet impact in increments of MOA. 1/4 is probably most common but there are others.

1/4 MOA at 100 yards is 1/4 inch. One "click" should adjust a 1/4 MOA scope 1/4" at 100 yards. That same click changes the impact by 1/4 MOA at ALL distances.

Let's say you adjust up one click. Your bullet should hit 1/4 MOA higher at 100 (1/4 inch), 1/4 MOA higher at 200 (1/2 inch) and even 1/4 MOA higher at 1000 yards... 2.5 inches.
 
Ok I think I get it now. As for range finding, so it's an experience thing, something that can't really be taught? That makes sense, I guess you slowly develop your "eye" for such things.
 
Most people strive to shoot 1 MOA which is 1" @ 100, 2" @ 200 as far as group size, however it should not be confused with a rifles tragectory, a rifle that shoots 1 MOA at 100, may shoot 3 MOA at 200, the farther out the bigger the difference, at 1000' yards a bullet may drop several feet. Really the only way to know how to adjust your scope is to shoot these differences and make notes as to where you hit.

I prefer using MIL adjustments over MOA beacause 1 MIL is 1 MIL, at any distance, eventually you develop a chart for how many MILs you adjust for differnt conditions such as distance, wind, temperature, cold bore... things like that.
 
Kimio said:
Ok *I think I get it now. As for range finding, so it's an experience thing, something that can't really be taught? That makes sense, I guess you slowly develop your "eye" for such things.
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Range estimating is very, very difficult. It can be learned but it takes a long time. It can be done with certain scopes (with mil lines/dots) if the target is of known size but few targets are, in the real world. Works well at the range, shooting known targets.

Most of us "estimate" range with something like this:

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This is not to discourage you from trying to learn but it gets very hard past about 50 yards.

A good way to learn is to have a laser rangefinder, guess the distance and then laser it. You'll get steadily better but it still takes a long time.
 
Go here and read the first few sentences after Minute-of-Angle for a great generic explanation. If you want to get real hairy into understanding more, delve deeper into the link.

http://www.snipercountry.com/articles/mildot_moa.asp

Some people get hung up on groups (which is good for them I suppose). I was taught 1st round counts as a hunter, 2nd shot should not be necessary if No 1 does the job.

But then, I don't shoot benchrest or for groups. Others do and like to know precisely where their holes will appear on paper. A good skill for some to have. Judging distance and doping wind are hard enough, which is why it is nice to know how well your rifle groups consistently, taking one big factor out of the equation.
 
Quick Example:

- Rifle Zero'd at 100 yards
- Target is found to be at at 600 yards (from Rangefinder)
- Bullet drop from 100-Yd zero = 6 feet = 72 inches (from Ballistics Table/or experience)
- 1 MinOfAngle ~ 1" at 100 (by definition), or 6" at 600 (simple ratio)
- Raise scope setting by 72/6 = 12 MOA

Most scopes aren't calibrated to a specific bullet/muzzle velocity and you have to dial in the actual MOA.
Military scopes can actually have this cartridge information built in, and you can simply move the dial to a pre-printed range.

Military sniper teams, however, make these calculations in about ½ second, ...and dream about them when sleeping.

Military scopes also have cross-hair stadia marks to assist in holdover without having to change the scope setting.
But those marks are based on an angle different from the "minute" of angle, and are another subject altogther.
 
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It has NOTHING to do with how the round acts due to gravity. It's simply a unit of measure for angular distance.
 
Just to clarify, in your original question, you mention a connection between MOA and gravity - that tells me that you are getting two different concepts confused with each other. Gravity effects bullet drop, not MOA.

MOA is how well grouped your shots are. The variables include the rifle itself, the ammo, and you. It is basically a measurement of how well you and your rifle can reproduce the exact same result on every shot. The standard concept of MOA is that it is equal to 1" for each 100 yards. Therefore a 1 MOA rifle will have 1" groups at 100 yards, 2" groups at 200 yards, etc.

Bullet drop is the effect of gravity on the bullet, and is entirely predictable, as gravity is a constant. The amount of drop at any given yardage is dependant solely on how long your bullet takes to get to that distance, since gravity will pull it down at exactly the same rate every time.

Drop really has no effect on MOA, but it will effect where your groups show up. For example, if your rifle is zeroed at 200 yards, and shoots 1 MOA, you can expect 2" groups (1 MOA @ 200 yards) centered around your point of aim(no drop because this is your zero distance). If it has a drop of 2" at 300 yards, you can expect 3" groups (1 MOA @ 300 yards) centered 2" below your point of aim (the amount of drop calculated for this distance).
 
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There are 360 'Degrees' on a compass...

Each 'Degree' is made up of 60 'Minutes'...

Each 'Minute' is made up of 60 'Seconds'...

One 'Minute' of Angle' (correctly called 'Minute Of Arc') is appx. 1" at 100 yards distance from the observer (shooter)...

HTH
 
Guys, Minute of Angle is just that, ...angle.

It can (and does) describe bullet dispersion or grouping (at any range).
It can (and does) describe bullet drop (or rise) from line-of-sight or horizontal for any cause at any particular range.
It can (and does) describe bullet windage left or right for any reason at any range.

MOA is just the angle from "zero-base" anything to describe where the bullet winds up.

And "1" MOA just happens to span ~"1" inch at "1"00 yards.
(So easy, ...a cave man can do the math) :D :D :D




Now if you really want to mess with your head, get into "mils" ;)
 
many rifles have mil dots or built in range finders but when it was explained to me how they are functioned it went way over my head
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All scopes and front sights have range finders.

Mil Dot or mils is not a whole lot different then MOA, only its mils. In reality is the same princable. As mentioned there are 360 degrees in a circle, 60 minutes in degree and 60 seconds in a minute.

There are 6400 mils ( actually 6283) in a circle. A mill is the angle subtended by 1 unit at a distance of 1000 yards.

The way a mil dot works is you have to know the size of your target.

Loot at your target through the scope and see how many mils dots or marks it takes to cover the target.

you take the size of the target in yards times 1000 then divide that by the number of mils that covers the target, that tells you how far away the target is.

An example. Lets say you have an 18 inch target. You look in the scope and see the target is covered by 2 mils. (mil dots). So you take 18 inches which is 1/2 yard times 1000 and you get 500 Divide 500 by the two mil dots that covers the target and you see that your target is 250 yards away.

A mil is 3.375 minutes.

Lets say you have a MOA scope with nothing but cross hairs. You can still use it as a range finder if you know the size of your target.

When you got your scope the paper work should tell you how many MOA the cross hairs cover at 100 yards.

Let say your cross hairs cover 3 inches at 100 yards. On the same 18 inch target it would be 1/6 the size of the target. At 200 yards it would be the cross hairs would cover 1/3 the size of the target. At 300, 1/2, all the way to 600 where the 3MOA cross hairs would be the same size.

So you see with practice if you know the size of your target, and the size of the cross hairs you can get pretty good at range estimation.

An easier way to do this. Take the same 3 MOA Cross hair. Divide that by 100 yards. That's .03. Use that number. Then any time you need to know the range. Divide the target by .03 and it will tell you how far away the target is if it's the same size as the cross hairs. Using the above example:

18/.03 = 600 yards. All you have to do is see the relationship between the cross hairs and the target to get the range to the target.

Anyway that's how we did it before Mil Dot scopes became popular.
 
The others above have explained that it is simply a unit of angular measurement, but I do want to point out that your initial comment is fundamentally incorrect...

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. A 1 MOA rifle should shoot one inch groups at 100 yards and for every 100 yards afterwards it should increase by 1 inch increments so 200yd = 2", 300yd =3" etc.
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Bullet travel is linear unless affected by outside forces- such as gravity and wind. When you hear a rifle as being described as "accurate to (or less than) minute of angle", this means that the hardware- the rifle and the ammunition- will place the bullets within roughly 1" at 100 yards- excluding any external influences- wind, gravity- and yes, the shooter. Best determined with the rifle locked in a solid rest to eliminate shooter error.

The effect of gravity on a bullet, is not linear. You no doubt understand that as the bullet travels downrange, it is bleeding off energy and velocity.
As it slows, the effect of gravity becomes much more pronounced. Bullets with a higher "BC" , or ballistic coefficient, are more efficient traveling through the air- and therefore maintain velocity better, are less affected by wind drift, and thus, "drop" less quickly than a bullet with a lower BC. Just look at the shape of a VLD bullet, vs. a soft point, or RN.

So, a bullet that drops 2" at 200 yards, may drop 6" at 400 yards- and not 4" as you seem to be thinking- because the bullet is losing velocity and will drop more per unit of distance traveled.

Hope this helps.
 
Even if the bullet does not slow down, shooting in a perfect vacuum for example, its path would still be a parabolic curve due to gravity. Gravity accelerates things downward, that is, the longer something falls, the faster it falls.

Double the time of flight and you quadruple the bullet's drop.
 
Very interesting thread. I don't know if this has anything to do with MOA, but why does the Red Dot in my optics work just fine at 10 yards, but at 25 yards with the same target that dot appears so darn large I can no longer see the bullseye and just have to shoot at the center of the paper. Does this dot get even larger at further distances (well, the target seems smaller at longer distances, dot size is not changing).

Are there better Red Dots out there that have a smaller dot, or is this just the way this type of optic functions? I am only asking in this thread because people have asked me if the optic I am using is 1, 2, 3 or whatever MOA.
 
at 25 yards with the same target that dot appears so darn large I can no longer see the bullseye
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It's just like holding your thumb in front of your eye. The relatively small object a few feet in front of you will still be visible on all sides of your thumb, but that same thumb is big enough to block out the entire moon.

The red dot is a constant size, but distance causes viewed objects to seem smaller, therefore they are more easily obscured by the dot.

There are different sizes available, with the smaller ones being designed to allow better visibility of the target at greater distances. I have never priced them myself, but I understand that the smaller dot models tend to run more expensive.
 
at 25 yards with the same target that dot appears so darn large I can no longer see the bullseye
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You can also do what I have always done for iron sights. Adjust the sight so that the point of impact is on the very top of the bead or dot instead of the center of it.
This is similar to the "six o'clock hold" employed by pistol bulleye target shooters.
 
A little more mud for clarity...;)
A bullet begins to drop the instant it clears the muzzle. Elevation is applied to counteract this for a given range (you can also get into battlesight or point-blank zero here). If you totally eliminate gravity (hence bullet drop), then yes, you would have MOA issues in the vertical plane.
 
Thank you everyone for the replies, this helps a whole lot. I'm still a novice shooter in many regards, I usually do pretty well put to 200 or 300 yards with irons but for he longest time the math an concept of how to accurately measure the distance and size of my target was lost to me.
 
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