General Questions

What Is MOA and Is It Really an Inch At 100 Yards?

MOA stands for Minute Of Angle. A full circle is divided into 360 degrees and each degree is divided into 60 minutes. Thus, there are 21,600 minutes in a full circle (360 x 60 = 21,600). A minute is a small angle, but it's exactly what's needed for gun sights. A rule of thumb is that changing a sight's elevation setting by 1 minute of angle changes the bullet's impact point by 1 inch at 100 yards. A more exact value and how it's arrived at is shown below:

A circle with a 100 yard radius (distance from the center to the edge) would have a circumference of approximately 628.32 yards or 22,619 inches (100 x 2 x pi = 628.32 {pi is about 3.1416}). Dividing the circumference in inches by the number of minutes in a full circle gives a value of about 1.047 inches (22619 / 21600 = 1.047). Thus, changing a sight's elevation setting by 1 minute of angle changes the bullet's impact point by 1.047 inches at 100 yards. And the bullet's impact point would change by 2.094 inches at 200 yards (1.047 x 2) and change by 3.141 inches at 300 yards (1.047 x 3).

MOA Diagram

 What is SAAMI? SAAMI stands for the Sporting Arms and Ammunition Manufacturers' Institute, Inc. SAAMI publishes a variety of standards for the production and testing of arms and ammunition. SAAMI is the standards setting body for ammunition and arms manufacturers in the U.S.A. With few exceptions, all commercial published ballistic coefficient (BC) values are based on the SAAMI G1 drag coefficient table or its derivatives.

What Are Standard Conditions?

Published downrange ballistics values for small arms usually use the following Standard Metro conditions:

 Altitude: 0 feet (0 meters) Temperature: 59º Fahrenheit (15º C) Pressure: 29.53 inches Hg (750 mm Hg) Humidity: 78 percent