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Posted: 11/19/2004 4:25:29 AM EDT
I feel kind of stuped asking this question, but I was wondering about it the other day and didn't have an answer.  If one shoots a "1 inch/1MOA shot group", what does that mean? Picture a perfectly round shot group - say 10 rounds. Does that mean the farthest from center impacts are 1 inch from center - for a 2 inch circle? Or is the diameter for the circle actually 1 inch making each impact 1/2 inch from center? Does my wording make sence? If not let me know. I would appreciate any help with this as it will allow me to better guage my shooting abilities knowing whether I'm shooting 1MOA or 2MOA etc. Thanks! |
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Use a micrometer or caliper to measure the OUTER edges of the two FARTHEST shots. Then subtract the diameter of the bullet from that measurement. This will give you the "group" size. To clarify: You want to measure from the center of the two farthest holes, but sometimes its hard to find the center of a hole. It's easier to measure from the edge. The diameter of the bullet = approx the radius of a hole * 2.  This isn't the most precise method, but gimme a break. You're fighting over thousandths of an inch on paper when target shooting, but in combat, its not going to matter. 
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+1 
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+1. This is the correct method. Regarding MOA, it's simple geometry. there are 360 degrees in a complete circle. Each degree is composed of 60 minutes of angle, each minute 60 seconds. It just so happens conveniently, that if you vary the line of trajectory by one minute of angle (1/60th of a degree of angle of the 360 degrees that compose a full circle), your point of impact will change by 1" at 100 yards. (The actual number is 1.047") SO it follows that at 200 yards, the point of impact will vary by 2" (if your line of trajectory is varying by 1 MOA), and 300 yards 3" and so on. Picture yourself at the center of a giant circle. If you're shooting 1" groups at 100 yards, it basically means that YOU and your GUN are lining up ALMOST exactly the same each shot. ALMOST means that your and your gun's variability between shots is only 1/60th of a degree! That's pretty incredible when you think about it. |
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