The Firing Line Forums - View Single Post - I'm looking for a technical definition of MOA

James K · December 30, 2000, 07:29 PM

Hi, Correia,

The question has been asked and answered before, but here it is in brief. A circle has 360 degrees, each of which is divided into 60 minutes and each minute into 60 seconds. Think of the protractor you had in grade school, with the little degree markings. If a rifle shooter is thought of as being at the center of the circle, the size of his group can be described in minutes of angle (MOA) or how big an arc the shots cover. By conicidence, one minute of angle equals about 1 inch at 100 yards, 2 inches at 200 yards, and so on.

So a rifle (and shooter) capable of placing a group of shots within a 1" circle at 100 yards is "shooting one minute of angle". Conventionally, groups are five shot unless otherwise specified, and group size is measured center to center of the farthest apart bullet holes. (If a center to center measurement is not feasible, the distance from the outside edges of the farthest apart holes can be measured, and the bullet diameter subtracted. This gives the same result.)

Jim

December 30, 2000, 07:29 PM	#4
James K Member In Memoriam Join Date: March 17, 1999 Posts: 24,383	Hi, Correia, The question has been asked and answered before, but here it is in brief. A circle has 360 degrees, each of which is divided into 60 minutes and each minute into 60 seconds. Think of the protractor you had in grade school, with the little degree markings. If a rifle shooter is thought of as being at the center of the circle, the size of his group can be described in minutes of angle (MOA) or how big an arc the shots cover. By conicidence, one minute of angle equals about 1 inch at 100 yards, 2 inches at 200 yards, and so on. So a rifle (and shooter) capable of placing a group of shots within a 1" circle at 100 yards is "shooting one minute of angle". Conventionally, groups are five shot unless otherwise specified, and group size is measured center to center of the farthest apart bullet holes. (If a center to center measurement is not feasible, the distance from the outside edges of the farthest apart holes can be measured, and the bullet diameter subtracted. This gives the same result.) Jim