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Rifles, Reloading, Optics, Equipment
Long Range Scopes and Other Optics
Dead on at 100yds 4inches right at 400yds
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<blockquote data-quote="greenejc" data-source="post: 2002582" data-attributes="member: 60453"><p>According to the JBM ballistic calculator, a 10 mph wind would drift about 10 inches at sea level if its a full value wind. A 5 mph wind is 4.6 inches to 5 inches at 400 yards. A 3 mph wind would drift it about 3 inches, and would be so slight that you might not even feel it. For a wind that light, you really need range flags. Since your group is impacting in line vertically, I think it has to be a really slight wind. A wind like that could come up between groups and not even be felt. I ran it on the Shooter's Calculator, too. You get a .93 inch drift for each mph of wind at 400 yards with your bullet, and mv. A 3.5 mph to 4 mph wind left to right will move the center of your group about 4 inches right, and may result in a difference in dispersion. The actual center of the group is about 3.2 inches right, and four of five rounds are within 1.4 inches vertically. The whole group is about 2.2 inches top to bottom. That's a 2 to 3 mph wind, not spin drift or misalignment of your scope, or improper technique. If you had poor technique, the group would be inconsistent. If the scope were canted, the group would be low and right. This is a slight wind that you didn't notice. Put up some wind flags and try again.</p></blockquote><p></p>
[QUOTE="greenejc, post: 2002582, member: 60453"] According to the JBM ballistic calculator, a 10 mph wind would drift about 10 inches at sea level if its a full value wind. A 5 mph wind is 4.6 inches to 5 inches at 400 yards. A 3 mph wind would drift it about 3 inches, and would be so slight that you might not even feel it. For a wind that light, you really need range flags. Since your group is impacting in line vertically, I think it has to be a really slight wind. A wind like that could come up between groups and not even be felt. I ran it on the Shooter's Calculator, too. You get a .93 inch drift for each mph of wind at 400 yards with your bullet, and mv. A 3.5 mph to 4 mph wind left to right will move the center of your group about 4 inches right, and may result in a difference in dispersion. The actual center of the group is about 3.2 inches right, and four of five rounds are within 1.4 inches vertically. The whole group is about 2.2 inches top to bottom. That's a 2 to 3 mph wind, not spin drift or misalignment of your scope, or improper technique. If you had poor technique, the group would be inconsistent. If the scope were canted, the group would be low and right. This is a slight wind that you didn't notice. Put up some wind flags and try again. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
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Dead on at 100yds 4inches right at 400yds
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