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Hunting
The Basics, Starting Out
Bullet drop compensation dials (BDC dials)
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<blockquote data-quote="Bart B" data-source="post: 108862" data-attributes="member: 5302"><p>[ QUOTE ]</p><p>Acctualy one moa at 100 yards is 1.047 inches most just round of to 1 inch for purposes of conversation.</p><p></p><p>[/ QUOTE ]More "actually," one minute of angle for shooting purposes has been exactly 1 inch at 100 yards in the USA for over 100 years. It's the trig minute of angle that's 1.047... inch at 100 yards. Kinda like the difference between a statute (land) mile of exactly 5280 feet and a nautical (ocean) mile having about 6080 feet.</p><p></p><p>The "shooting" MOA is based on the standard 30 inch iron sight radius on early 1900's target rifles and the target's scoring rings having even inches in diameters. Plus the external scope mount's spacing of 7.2 inches. </p><p></p><p>One shooting MOA is equal to exactly 1/3600th of the sight adjustment radius or range. With a 30-inch sight radius, that's equal to .00833-inch movement on the rear sight; exactly 1/3rd of a turn (4 quarter minute clicks) on their 40 threads per inch lead screws. And also equal to .002-inch rear scope mount movement (also 4 quarter minute clicks with the same thread count), or 1/3600th of the 7.2-inch mount radius or base spacing.</p><p></p><p>In contrast, European sight adjustments have typically made changes on the target in metric units; 1mm or 2mm at 50 metres or 1cm at 100 metres. They've adopted the USA shooting MOA for some of their rifle scopes.</p></blockquote><p></p>
[QUOTE="Bart B, post: 108862, member: 5302"] [ QUOTE ] Acctualy one moa at 100 yards is 1.047 inches most just round of to 1 inch for purposes of conversation. [/ QUOTE ]More "actually," one minute of angle for shooting purposes has been exactly 1 inch at 100 yards in the USA for over 100 years. It's the trig minute of angle that's 1.047... inch at 100 yards. Kinda like the difference between a statute (land) mile of exactly 5280 feet and a nautical (ocean) mile having about 6080 feet. The "shooting" MOA is based on the standard 30 inch iron sight radius on early 1900's target rifles and the target's scoring rings having even inches in diameters. Plus the external scope mount's spacing of 7.2 inches. One shooting MOA is equal to exactly 1/3600th of the sight adjustment radius or range. With a 30-inch sight radius, that's equal to .00833-inch movement on the rear sight; exactly 1/3rd of a turn (4 quarter minute clicks) on their 40 threads per inch lead screws. And also equal to .002-inch rear scope mount movement (also 4 quarter minute clicks with the same thread count), or 1/3600th of the 7.2-inch mount radius or base spacing. In contrast, European sight adjustments have typically made changes on the target in metric units; 1mm or 2mm at 50 metres or 1cm at 100 metres. They've adopted the USA shooting MOA for some of their rifle scopes. [/QUOTE]
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The Basics, Starting Out
Bullet drop compensation dials (BDC dials)
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