Flyboy_451
New member
A couple of recent posts have got me to thinking about how to explain how difficult long range shooting with a handgun can be. I do a lot of long range plinking with big bore sixguns out to some pretty incredible ranges, but rarely even try to take long shots on game animals in the field. For the purpose of this post, long range would be 100 yards and beyond.
Before getting into the mechanics of shooting at long range, I will attempt to explain the term "minute of angle" first. This is of key importance to being able to follow the numbers of this post.
Angles are expressed in degrees and fractions of a degree. Think in terms of time. We divide degrees into minutes and seconds. 60 seconds=1 minute, and 60 minutes=1 degree. Sounds simple, right?
well, here is where some get confused. We often speak of accuracy in terms of minutes of angle (MOA), but what exactly does this mean? It is simply an angular measurement that defines another measurement at a given distance. Imagine two lines that originate at the same point, but diverge in direction by 1/60 of a degree, or 1MOA. If you extended these lines to 100 yards, and then measured the distance between where they terminated, the distance between the two points would be 1.0472 inches. If the lines were extended to 200 yards, the measurement between the two points would be double that, or 2.0944 inches. At 300 yards, 3.141 inches, and so on. Keep in mind that MOA is an angular measurement, so as you extend the range, the distance between the two lines grows at a constant rate. Got it? Good!
For the purposes of this discussion, I will round down so that 1MOA=1 inch at 100 yards, 2" @ 200 yards, etc. This is typical when talking about shooting.
Now onto the reason that you need to understand this. To engage targets successfully at longer ranges, your sight alignment must be perfect, and it is my intent to show you how perfect i mean. By understanding angular measurements, and employing trigonometry, we can calculate how much movement of the front sight in relation to the rear sight, displaces the bullet a given amount at a given distance. We can also make a very educated guess as to whether or not we are capable of a given shot based on our own abilities at shorter ranges.
First, let's define the size of the target that we intend to engage. For the purposes of hunting deer sized game, I think a target area of 10 inches is very suitable. It also makes for easy numbers to work with for this example.
Using a target area of ten inches in diameter means that we would want our bullet to impact no more than five inches in any direction from the center. In other words, we must hold our sights on the exact center of the target, plus or minus five inches. At 100 yards, 5 inches equals five minutes of angle.
So, how much sight movement equals a given amount of aiming error at any given distance? This is where the trigonometry comes in. This must be calculated for the individual gun, based on the sight radius, or the distance from the rear sight to the front sight. Imagine a perfect sight picture, with the front sight perfectly level with and dead center of the rear sight. Now imagine a misalignment in any direction. The distance that the front sight moves to cause this misalignment is what I am talking about. How much movement is equal to 1MOA?
I measured the sight radius on my 5 1/4" .475 Linebaugh at about 7 1/4". By using trig, I calculated that a front sight movement of only .00211" is equal to 1MOA of misalignment. To put this in perspective, this is a measurement that is roughly equal to half the thickness of a piece of printer paper. This will shift the bullet impact by one inch at 100 yards. Now we can figure how much misalignment we can tolerate before our bullet leaves the 10 inch intended target area. All we have to do is multiply by five, and we get .01055", or roughly the thickness of two pieces of printer paper. This is if we were able to place our sights precisely in the center of our ten inch target area and hold them there. An error in sight alignment so small as to be nearly impossible to see, would cause out bullet to miss it's intended mark at one hundred yards. At two hundred yards, the amount of error that is allowable is cut in half. Remember that we are talking about angular changes, while still trying to hit the same 10 inch target area. At two hundred yards, our five inches of deviation from center is equal to 2.5MOA.
The following are sight misalignment distances that I calculated for other sight radii.
sight radius- Misalignment- MOA
12 .0034 1
12 .0174 5
14 .0040 1
14 . 0203 5
16 .0046 1
16 .0232 5
As you can see, as the sight radius gets longer, the misalignment value for a given angular error also increases. This is why guns with a longer sight radius are easier to shoot accurately. The error in sight alignment is larger, and thus easier to see. But, even with a 16 inch sight radius, a 5MOA angle is only a movement of the front sight of .0232”, or roughly the thickness of four sheets of paper.
Next time you are thinking of taking that 200 yard shot on a trophy buck, keep this in mind. This doesn’t even take bullet drop and wind drift into account. That is a whole other subject!!
Before getting into the mechanics of shooting at long range, I will attempt to explain the term "minute of angle" first. This is of key importance to being able to follow the numbers of this post.
Angles are expressed in degrees and fractions of a degree. Think in terms of time. We divide degrees into minutes and seconds. 60 seconds=1 minute, and 60 minutes=1 degree. Sounds simple, right?
well, here is where some get confused. We often speak of accuracy in terms of minutes of angle (MOA), but what exactly does this mean? It is simply an angular measurement that defines another measurement at a given distance. Imagine two lines that originate at the same point, but diverge in direction by 1/60 of a degree, or 1MOA. If you extended these lines to 100 yards, and then measured the distance between where they terminated, the distance between the two points would be 1.0472 inches. If the lines were extended to 200 yards, the measurement between the two points would be double that, or 2.0944 inches. At 300 yards, 3.141 inches, and so on. Keep in mind that MOA is an angular measurement, so as you extend the range, the distance between the two lines grows at a constant rate. Got it? Good!
For the purposes of this discussion, I will round down so that 1MOA=1 inch at 100 yards, 2" @ 200 yards, etc. This is typical when talking about shooting.
Now onto the reason that you need to understand this. To engage targets successfully at longer ranges, your sight alignment must be perfect, and it is my intent to show you how perfect i mean. By understanding angular measurements, and employing trigonometry, we can calculate how much movement of the front sight in relation to the rear sight, displaces the bullet a given amount at a given distance. We can also make a very educated guess as to whether or not we are capable of a given shot based on our own abilities at shorter ranges.
First, let's define the size of the target that we intend to engage. For the purposes of hunting deer sized game, I think a target area of 10 inches is very suitable. It also makes for easy numbers to work with for this example.
Using a target area of ten inches in diameter means that we would want our bullet to impact no more than five inches in any direction from the center. In other words, we must hold our sights on the exact center of the target, plus or minus five inches. At 100 yards, 5 inches equals five minutes of angle.
So, how much sight movement equals a given amount of aiming error at any given distance? This is where the trigonometry comes in. This must be calculated for the individual gun, based on the sight radius, or the distance from the rear sight to the front sight. Imagine a perfect sight picture, with the front sight perfectly level with and dead center of the rear sight. Now imagine a misalignment in any direction. The distance that the front sight moves to cause this misalignment is what I am talking about. How much movement is equal to 1MOA?
I measured the sight radius on my 5 1/4" .475 Linebaugh at about 7 1/4". By using trig, I calculated that a front sight movement of only .00211" is equal to 1MOA of misalignment. To put this in perspective, this is a measurement that is roughly equal to half the thickness of a piece of printer paper. This will shift the bullet impact by one inch at 100 yards. Now we can figure how much misalignment we can tolerate before our bullet leaves the 10 inch intended target area. All we have to do is multiply by five, and we get .01055", or roughly the thickness of two pieces of printer paper. This is if we were able to place our sights precisely in the center of our ten inch target area and hold them there. An error in sight alignment so small as to be nearly impossible to see, would cause out bullet to miss it's intended mark at one hundred yards. At two hundred yards, the amount of error that is allowable is cut in half. Remember that we are talking about angular changes, while still trying to hit the same 10 inch target area. At two hundred yards, our five inches of deviation from center is equal to 2.5MOA.
The following are sight misalignment distances that I calculated for other sight radii.
sight radius- Misalignment- MOA
12 .0034 1
12 .0174 5
14 .0040 1
14 . 0203 5
16 .0046 1
16 .0232 5
As you can see, as the sight radius gets longer, the misalignment value for a given angular error also increases. This is why guns with a longer sight radius are easier to shoot accurately. The error in sight alignment is larger, and thus easier to see. But, even with a 16 inch sight radius, a 5MOA angle is only a movement of the front sight of .0232”, or roughly the thickness of four sheets of paper.
Next time you are thinking of taking that 200 yard shot on a trophy buck, keep this in mind. This doesn’t even take bullet drop and wind drift into account. That is a whole other subject!!
