kingcheese
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Im pretty sure that MOA stands for minute of angle, but what exactly is envolved in shooting MOA, i just cant quit grasp the concept of it
what is MOA
- Thread starter kingcheese
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menacingsquirrel
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Here's a website that goes into an explanation:
http://riflestocks.tripod.com/moa.html
Unfortunately, I think it become over emphasized/hyped on the internets...
http://riflestocks.tripod.com/moa.html
Unfortunately, I think it become over emphasized/hyped on the internets...
Tom488
Member
Put simply, a minute of angle is 1/60th of a degree. If you were to pick a point in space, and draw a line 100 yards long, then draw another line from the same point one MOA away from your first line, it would wind up being 1" away from your first line at 100 yards out. That's because, at 100 yards, 1 MOA is roughly equal to 1 inch of distance (actually, 1.047 and change).
So... if you fire a 5-shot group at a 100 yard, and the maximum distance between shots is 3", you would call that a 3 MOA group.
If you fired the same 3" group at a 200 yard target, that would be a 1.5 MOA group. That's because, while 1 MOA = 1 inch at 100 yards, 1 MOA = 2 inches at 200 yards (and 3" at 300 yards, 4" at 400 yards, etc.). The inverse is true with distances shorter than 100 yards. For instance, a 3" group at a 50 yard target would be a 6 MOA group.
Think of it as a cone, like the beam of a flashlight, extending out from your muzzle and onto your target. If the "beam" were 1MOA in size, it would shine a 1" circle on the target at 100 yards. Put another way, if you have a rifle that's guaranteed to shoot 1MOA, then every shot would end up within a 1" circle around your aiming point, if you were shooting at 100 yards.
So... if you fire a 5-shot group at a 100 yard, and the maximum distance between shots is 3", you would call that a 3 MOA group.
If you fired the same 3" group at a 200 yard target, that would be a 1.5 MOA group. That's because, while 1 MOA = 1 inch at 100 yards, 1 MOA = 2 inches at 200 yards (and 3" at 300 yards, 4" at 400 yards, etc.). The inverse is true with distances shorter than 100 yards. For instance, a 3" group at a 50 yard target would be a 6 MOA group.
Think of it as a cone, like the beam of a flashlight, extending out from your muzzle and onto your target. If the "beam" were 1MOA in size, it would shine a 1" circle on the target at 100 yards. Put another way, if you have a rifle that's guaranteed to shoot 1MOA, then every shot would end up within a 1" circle around your aiming point, if you were shooting at 100 yards.
henschman
Member
Yep, a MOA is 1/60 of a degree, which is almost exactly equal to 1 inch per 100 yards.
When it comes to shooting, you need to talk in terms of angle rather than in linear distance, because angle is independent of distance.
MOA are used to measure 2 things when it comes to shooting: the size of a shot group, and the sight correction needed to get on target.
MOA being used to measure the size of a group was already explained pretty well above.
When it comes to adjusting the sights on a rifle, you need to measure the adjustent in angle because rifle sights do not adjust in linear distance... they adjust in angle. When you are not sighted in, your sights are pointed one way, while the path your bullet travels is pointed in another way. You can measure the angle that they are off from one another, and correct it.
It is easy to measure the angle as long as you know the distance to your target, because 1 MOA = 1 inch per 100 yards. Just measure how many inches off target you are, in both windage and elevation, and then convert that to minutes, and move your sights the necessary number of MOA. If you're 9" left at 300 yards, you know that 1 MOA is 3" at 300, so you are 3 MOA left. You then just have to know how many MOA each click moves your rifle's sights. If you have a scope with 1/4 MOA clicks, it means you have to make 4 clicks to move it 1 MOA. So if you needed to adjust 3 MOA left, you would have to make 12 clicks left.
When it comes to shooting, you need to talk in terms of angle rather than in linear distance, because angle is independent of distance.
MOA are used to measure 2 things when it comes to shooting: the size of a shot group, and the sight correction needed to get on target.
MOA being used to measure the size of a group was already explained pretty well above.
When it comes to adjusting the sights on a rifle, you need to measure the adjustent in angle because rifle sights do not adjust in linear distance... they adjust in angle. When you are not sighted in, your sights are pointed one way, while the path your bullet travels is pointed in another way. You can measure the angle that they are off from one another, and correct it.
It is easy to measure the angle as long as you know the distance to your target, because 1 MOA = 1 inch per 100 yards. Just measure how many inches off target you are, in both windage and elevation, and then convert that to minutes, and move your sights the necessary number of MOA. If you're 9" left at 300 yards, you know that 1 MOA is 3" at 300, so you are 3 MOA left. You then just have to know how many MOA each click moves your rifle's sights. If you have a scope with 1/4 MOA clicks, it means you have to make 4 clicks to move it 1 MOA. So if you needed to adjust 3 MOA left, you would have to make 12 clicks left.
So, knowing MOA is basically a way to express the cone of dispersion in shots fired, what is good or bad?
Military standards - as far back as the 1950's, and certainly even earlier, is a 2MOA group of ten shots using the milspec rifle and ammo. That means it's a 10" group at 500 yards. And the standard is with ten - 10 - shots, not less. The reason is that probability and statistics math show that a ten shot group is an accurate presentation of what the barrel really does. Less - like three or five shot groups - can leave the shooter with a sample, not the whole picture. Adjust the sights using three shot groups and shooters often end up "chasing the zero." It's because that center point of the group doesn't represent the actual - it's only three random shots worth of information, not a full sample, and certainly not from a fully warmed up barrel - which military guns will have.
Some insist the first shot from a cold barrel is more representative of what will happen. I have no problem with that for hunting, I just question why buy a barrel that shifts the point of aim that much when warmed up, and whether it's even worth the bother. Again, a 2MOA barrel shoots a 10" group at 500 yards - hunting medium game means it will be about half the size of the 18" kill zone on whitetail deer or larger. For combat, humans use the same 18" zone.
On small game at distance, like prairie dogs, things are much more challenging. There you have 200 to 500 yard shots at 6 to 8" targets, and even a 1MOA gun at 500 yards, with a 5" group size, will miss a skinny dog standing up. 1/2MOA guns, or at least a 2" group at whatever distance the dogs are at, is the preferred maximum, and the shooter is still left with getting a powerful enough scope with enough elevation adjustment to use, plus wind, mirage, and their buddy getting it first.
What's happened in some circles is a MOA result becomes comparative and gets ranked by those who like having social heirarchies, and the testosterone challenged logic starts up with "My MOA is better than yours." Long distance precision shooters see that in their rankings, along with calling the wind and interpreting mirage, but when hunting most North American game, or in most combat, 2MOA is the standard. Most guns shoot it, just like most cars have enough power to pull away from the curb and get you to work. "Mine's better which makes me better" should be left on a competition range where the results will be posted for all to see. In forums, it's the typical braggadocio of an anonymous poster with no way to actually rate it - which everyone should understand is worthless as the pixels it's described on.
It's really all about shooter skills, Alvin York wasn't issued a sniper rifle, and Carlos Hathcock was using a milspec issue M2 .50 cal on a standard tripod when he made the reputedly longest shot in the Vietnam war. Master carpenters don't have magic hammers, and good shooters are with any gun.
Military standards - as far back as the 1950's, and certainly even earlier, is a 2MOA group of ten shots using the milspec rifle and ammo. That means it's a 10" group at 500 yards. And the standard is with ten - 10 - shots, not less. The reason is that probability and statistics math show that a ten shot group is an accurate presentation of what the barrel really does. Less - like three or five shot groups - can leave the shooter with a sample, not the whole picture. Adjust the sights using three shot groups and shooters often end up "chasing the zero." It's because that center point of the group doesn't represent the actual - it's only three random shots worth of information, not a full sample, and certainly not from a fully warmed up barrel - which military guns will have.
Some insist the first shot from a cold barrel is more representative of what will happen. I have no problem with that for hunting, I just question why buy a barrel that shifts the point of aim that much when warmed up, and whether it's even worth the bother. Again, a 2MOA barrel shoots a 10" group at 500 yards - hunting medium game means it will be about half the size of the 18" kill zone on whitetail deer or larger. For combat, humans use the same 18" zone.
On small game at distance, like prairie dogs, things are much more challenging. There you have 200 to 500 yard shots at 6 to 8" targets, and even a 1MOA gun at 500 yards, with a 5" group size, will miss a skinny dog standing up. 1/2MOA guns, or at least a 2" group at whatever distance the dogs are at, is the preferred maximum, and the shooter is still left with getting a powerful enough scope with enough elevation adjustment to use, plus wind, mirage, and their buddy getting it first.
What's happened in some circles is a MOA result becomes comparative and gets ranked by those who like having social heirarchies, and the testosterone challenged logic starts up with "My MOA is better than yours." Long distance precision shooters see that in their rankings, along with calling the wind and interpreting mirage, but when hunting most North American game, or in most combat, 2MOA is the standard. Most guns shoot it, just like most cars have enough power to pull away from the curb and get you to work. "Mine's better which makes me better" should be left on a competition range where the results will be posted for all to see. In forums, it's the typical braggadocio of an anonymous poster with no way to actually rate it - which everyone should understand is worthless as the pixels it's described on.
It's really all about shooter skills, Alvin York wasn't issued a sniper rifle, and Carlos Hathcock was using a milspec issue M2 .50 cal on a standard tripod when he made the reputedly longest shot in the Vietnam war. Master carpenters don't have magic hammers, and good shooters are with any gun.
Art Eatman
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