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<blockquote data-quote="Bart B" data-source="post: 105595" data-attributes="member: 5302"><p>Brown Dog, I think you're using 1.047197536428... inch at 100 yards as one minute of angle. That's trigonometry; the sine of one trig MOA (0.00029088820...) multiplied by 100 yards (3600 inches). I divided your 800-yard 76.9cm come up from 100 yards by your 28.9 MOA and got 2.6609, then divided that by 1.0472 and got 2.54...cm. That more or less got me thinking.</p><p></p><p>The shooting industry in the USA uses exactly 1 inch at 100 yards as a "shooting" minute of angle. That's based on the original sight radius of 30 inches on early target rifles with their rear (or back) sight moving .025-inch per revolution (their lead screws having 40 threads per inch) for three MOA per turn or .008333-inch (1/3rd turn) per minute of angle. The shooting MOA is 1/3600th of the distance; 30 inches divided by 3600 is .008333 inch. </p><p></p><p>It's also based on external adjustments on target scopes with the mounts spaced the standard 7.2 inches apart and each four 1/4th MOA clicks moving the rear adjustment .002-inch; .0005-inch per click. 7.2 inches divided by 3600 is .002-inch. Modern scopes are marked and specified for 1/4th inch per click at 100 yards although their manufacturing methods may have it a tiny bit off.</p><p></p><p>Most centerfire competition targets in the USA have scoring rings spaced on this shooting MOA standard. I used 1 inch equals 1 MOA at 100 yards for my data. That's probalby why our SWAGging and SWAPping data are different.</p></blockquote><p></p>
[QUOTE="Bart B, post: 105595, member: 5302"] Brown Dog, I think you're using 1.047197536428... inch at 100 yards as one minute of angle. That's trigonometry; the sine of one trig MOA (0.00029088820...) multiplied by 100 yards (3600 inches). I divided your 800-yard 76.9cm come up from 100 yards by your 28.9 MOA and got 2.6609, then divided that by 1.0472 and got 2.54...cm. That more or less got me thinking. The shooting industry in the USA uses exactly 1 inch at 100 yards as a "shooting" minute of angle. That's based on the original sight radius of 30 inches on early target rifles with their rear (or back) sight moving .025-inch per revolution (their lead screws having 40 threads per inch) for three MOA per turn or .008333-inch (1/3rd turn) per minute of angle. The shooting MOA is 1/3600th of the distance; 30 inches divided by 3600 is .008333 inch. It's also based on external adjustments on target scopes with the mounts spaced the standard 7.2 inches apart and each four 1/4th MOA clicks moving the rear adjustment .002-inch; .0005-inch per click. 7.2 inches divided by 3600 is .002-inch. Modern scopes are marked and specified for 1/4th inch per click at 100 yards although their manufacturing methods may have it a tiny bit off. Most centerfire competition targets in the USA have scoring rings spaced on this shooting MOA standard. I used 1 inch equals 1 MOA at 100 yards for my data. That's probalby why our SWAGging and SWAPping data are different. [/QUOTE]
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