Scope adjustment for long range shooting

J

J-red

Guest
Hello,
I'm new to benchrest shooting but have been shooting all my life. A local shooting range held a match a few weeks ago and I went (15 bucks to shoot at an extended range... why not!). I had previously never shot past 100 yards (that's the longest range i have access to) and this match required 10 shots each at 100, 200, and 300 yards. I shot a 26" barreled 223 and put together some ballistics so that it would be on the paper at the longer ranges. The ballistics table called for 4" of drop at 200 yards and the man next to me agreed that it was typical of his 223 so I dialed in 4" of elevation on my scope (1/4" clicks = 16 clicks total). The results? a nice group about 4" high from center. odd, but maybe the longer barrel made a difference, right? On to the 300 yard targets...

At 300 yards I was expecting about 16" of drop and adjusted accordingly (1/4" clicks = 64 clicks). This time, the rounds grouped at about 2" but nearly 10" above the center of the target!

At this point, the fellow next to me figured out what was going on and told me this: 1" (4 clicks) = 1" at 100 yards BUT the same 4 clicks makes a 2" difference at 200 yards and a three inch difference at 300 yards. I tried it on the next round and sure enough, at 200 yards 8 clicks (2" at 100 yards) put me right on center. Then again on the third round i dialed in 25 clicks (5" at 100 yards = 15" at 300 yards) and all ten rounds landed in the x-ring.

All this to say... Is this really how it works or am i confused?
 
Yes, you have it right. The one thing that sometimes gets overlooked is that scope adjustments are really in fractions of a degree. The directions that say 1/4" at 100 yards are really telling you that the value of the smallest increment available will give that much change in point of impact at 100 yards. That same click will give 1/16" @ 25 yd.,1/8@50, 1/4@100, 1/2@200, 3/4@300, 1"@400,etc. BTW MOA stands for minute of angle, which is 1/60th of a degree; so 1/4 MOA adjustments are the equivalent of 1/240 of a degree.
 
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