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Posted: 4/24/2007 5:46:27 AM EDT
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I have my .223 varmit rifle zeroed at 100 yards. Here are the specs. RRA forged lower, mil-spec forged flat top upper with 24" 1:8 twist match grade stainless bull barrel. The turrets on the side and top of my scope say "1 click = 1/8" @ 100" So I know 1 click will move the bullet impact 1/8" at 100 yards. The ballastics for the Federal 69 grain Sierra Matchking Ammo I am using says I will have -3.5 inches of bullet drop at 200 yards and -13.3 at 300 yards. So here is the dumb question. How many clicks do I need to adjust to hold my cross hairs dead on at 200 yards and 300 yards? Pics of the rifle and groups are forthcomming....... |
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An easy way to remember it is that 8 clicks on your scope moves 1" at 100 yards, 2" at 200 yards, 3" at 300 yards, etc. Here's the math and rough physics. A 1/8 MOA click is 1/8" at 100 yards, 2/8" (1/4") at 200 yards, and 3/8" at 300 yards. To correct for -3.5" at 200 yards, you'd adjust 4 clicks per inch (1/4" per click), or 4 x 3.5" = 14 clicks (alternately 3.5/0.25=14 clicks). Since your bullet will be striking low, you'll adjust the dials in the direction to bring the bullet impact up, which means you want to raise the barrel. To correct for -13.3" at 300 yards, you'll adjust 3/8" (0.375") per click, or 2.67 clicks per inch. 2.67x13.3 or 13.3/0.375 gives 35.5 clicks; round down to 35. It's actually closer to 0.39, which will give you 34 clicks, but we're using the simple version of 1"=1 MOA at 100 yards. Interestingly for those who care about the math, 1 MOA at 300 yards is pi. That's easy to remember! |
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