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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
What does MOA means?
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<blockquote data-quote="Bart B" data-source="post: 1150707" data-attributes="member: 5302"><p>The subtended angle a MOA has was simplified for the shooting sports in the USA over a century ago as 1 inch per hundred yards of range. As all the smallbore and high power rifle targets had then and today have scoring rings based on inch intervals, that made things easy to do. 1 MOA equalled 1/3600th of the range. One inch for every hundred yards of range.</p><p></p><p>Metallic rear sights made in the USA and some other places for target use had then and still do have 40 tpi threads on their adjustments. One turn move the rear sight .025" and with the standard 30 inch sight radius for 24" barrels, that equated to 3 MOA per turn over 12 clicks. 1/3600th of 30 inches is .00833" and that multiplied by 3 equals .025" 1/4 MOA per click.</p><p></p><p>Externally adjusted target scope bases had a standard spacing of 7.2 inch. 1/3600th of that equals .002", so with the adjustment threads at 40 tpi and 50 clicks of them for one turn, 4 clicks moved the adjustment .002". Again, one MOA for 4 clicks. 1/4 MOA per click.</p><p></p><p>In the 1960's folks using their brand new fangled digital calculators learned the sine of 1 MOA of angle was 0.00029088820456342459637429741574.... and that multiplied by 3600 inches in a hundred yards gave 1.047197536428328546947470696664... inch per hundred yards.</p><p></p><p>Those that insist on perfection and exact stuff never move a 100 yard target with inch spaced scoring rings to about 95 yards so their spacing more closely equals what a trig MOA subtends.</p></blockquote><p></p>
[QUOTE="Bart B, post: 1150707, member: 5302"] The subtended angle a MOA has was simplified for the shooting sports in the USA over a century ago as 1 inch per hundred yards of range. As all the smallbore and high power rifle targets had then and today have scoring rings based on inch intervals, that made things easy to do. 1 MOA equalled 1/3600th of the range. One inch for every hundred yards of range. Metallic rear sights made in the USA and some other places for target use had then and still do have 40 tpi threads on their adjustments. One turn move the rear sight .025" and with the standard 30 inch sight radius for 24" barrels, that equated to 3 MOA per turn over 12 clicks. 1/3600th of 30 inches is .00833" and that multiplied by 3 equals .025" 1/4 MOA per click. Externally adjusted target scope bases had a standard spacing of 7.2 inch. 1/3600th of that equals .002", so with the adjustment threads at 40 tpi and 50 clicks of them for one turn, 4 clicks moved the adjustment .002". Again, one MOA for 4 clicks. 1/4 MOA per click. In the 1960's folks using their brand new fangled digital calculators learned the sine of 1 MOA of angle was 0.00029088820456342459637429741574.... and that multiplied by 3600 inches in a hundred yards gave 1.047197536428328546947470696664... inch per hundred yards. Those that insist on perfection and exact stuff never move a 100 yard target with inch spaced scoring rings to about 95 yards so their spacing more closely equals what a trig MOA subtends. [/QUOTE]
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What does MOA means?
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