Minute of Angle: The Measure of Accuracy in your Rifle
Minute of Angle (MOA) is the term used as the standard for measuring the accuracy of a hunting rifle.You can also use minute of angle as a means of measuring the size of an animal’s target zone.In the simplest terms, there are 360 degrees in a circle, each degree has 60 minutes.The calculated distance extended to a target at 100 yards is 1.047 inches or “one-minute.” This number is just a crosshair over “one inch” and to make calculating easier, most all hunters and shooters use “one inch,” this is called “shooter’s minute of angle.”In terms of accuracy, if a hunter and his/her rifle can shoot three or five rounds and have them groupinside one inch at 100 yards, then you have a minute of angle group, or a minute of angle rifle.
The rifle scopes and the scope clicks have a MOA value also. Most hunters use 1/8 inch and the 1/4 inch MOA click value. Using the 1/4 inch scope, this means that each click equals 1/4 inch of movement at 100 yards. So in order to make the bullet impact move one inch or one MOA at 100 yards, you must turn the elevation or the windage knob four clicks. The click value moves up by a 1/4 inch for each 100-yard increase in distance, so 200 yards will be ½ inch movement per click, 300 yards will be 3/4 in. per click, 400 yards = 1 in.,500 yards = 1 1/4 in., 600 yards = 1 ½ in., 700 yards = 1 3/4 in., 800 yards = 2 in., 900 yards = 2 1/4 in. and 1000 yards = 2 ½ inches of movement per click of elevation or windage knob on your rifle scope.
Speaking of accuracy at distance, this angle stays consistent all the way out to how ever far you want to shoot. One inch at 100 yards, two inches at 200 yards, three inches at 300 yards, four inches at 400 yards and so on. So if a hunter can shoot an eight inch-group at 800 yards, or a ten-inch group at 1000 yards, that is minute of angle grouping. And you are an accurate shot. It is possible to be accurate with a 2-inch group at 100 yards, on deer sized game, but your accuracy will only go so far. At 200 yards your group will open up to 4 inches, this is good; at 300 yards your group opens up 7 to 8 inches, a hit will still be made, but is getting marginal for correct shot placement. At 400 yards your group opens up to 12 to 16 inches and getting marginal for a hit. At 500 yards and beyond, your groups only open up more and morea miss is highly likely, depending on wind, conditions and setup.
It is possible to shoot better than minute of angle. “Sub” minute of angle. If your rifle shoots ½ inch groups at 100 yards, you could say half minute of angle or sub-MOA in describing your groups or your rifle. 2.99 inches or better at 300yards, 6.99 inches or better at 700 yards, or a 10-inch group at 1100 yards can all be described as sub-minute of angle.
While hunting, out in the field, you can also describe how you will “hold” your aim, or cross-hairs of the scope on a game animal. You can know how big the game animal you target is, beforehand. A Mule Deer has a body height of approximately 15 inches from top of the back to brisket, give or take an inch. So at 400 yards, one MOA is four inches. You could say that a Mule Deer standing at 400 yards is 4 MOA tall or 16 inches.
Say, for example, you know the trajectory of your rifle-scope-and bullet combination,(AND ITS A "MUST" THAT YOU KNOW!!) and you have a 300 Yard "Zero", and know that at 400 yards that your bullet drops 8 inches, (or 2 MOA) and that Mule Deer standing there has a "vital zone" of 15 inches by 15 inches square; you could aim and place the cross-hairs of your scope right at the top of the deer's back, squeeze off a shot, and expect a hit, because you have "confirmed" many times over at the shooting range, and on steel targets, that your bullet drops 8 inches/
2 MOA from 300 to 400 yards.
To be Proficient at Extended Distances, You Must Know, by Confirming Exactly what Your Bullet is Doing from 400 to 500, 500 to 600, 600 to 700 yards, etc., All the Way Out to however Far you want to Shoot!!
Listed in the table below, are kill-zone measurements (top of back-to-chest, front-chest to back-of-ribs) of various game animals. These are approximate field measurements (in inches), as every animal is different. Your shots and point-of-aim should be centered in the middle of this imaginary square, on the shoulder of game animals.
Coues Deer, Blackbuck, Pronghorn, Javelina Boar, Coyote, 12-14 in.
Axis Deer, Whitetail Deer, Wolf 14-16 in.
Mountain Lion, Dall Sheep, Mule Deer 13-17 in.
Big Horn Sheep, Stone Sheep, Mtn. Goat, Caribou 18-20 in.
Rocky Mountain, Roosevelt Elk, Black Bear, 20-24 in.
Brown, Grizzly and Polar Bear 30-38 in.
Moose, Eland, Cape Buffalo 30-36 in.
Bison Buffalo 40 in.
Tule Elk . 18-22 in.
By understanding and communicating in minute of angle, you will know how your rifle will perform and how big your target area is on a game animal, at any given distance. The practice and use of this information, will make your shots more preciseat the shooting range, and in the field.
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