Exterior Ballistics- Is Something Missing?

Dan Conzo

Well-Known Member
Dec 5, 2001
Nanty-Glo, Pennsylvania
Is there something missing in our exterior ballistic formula? Example: a 30 caliber 190 gr Sierra MK w/ a BC of .533, w/ a muzzle velocity of 3200 fps has a wind drift of 67.45" in a 10 mph crosswind @ 1000 yds. A 6mm 107 gr Sierra MK w/ approx the same BC .527, w/ the same muzzle velocity and the same remaining velocity, also has the same wind drift @ 1000 yds (68.73") w/ a 10 mph crosswind. It seems that in 6.5mm, 7mm, 30, and 338 this is accurate, but if you were in a shoot-off @ 1000 yd competition and you had your 30 cal (w/ above load) and your 6mm (w/ above load) both rifles being equal in the accuracy department and the wind started to pick up heavy (crosswind) which rifle would you use? Most people I know would use the 30.


Dave King

Well-Known Member
May 3, 2001
It's hard for folks to believe that the heavier bullet won't have better 'wind bucking' characteristics. If the BC is the same and the initial velocity is the same the two should be essentially equal.

Yes, I'd probably be inclined to pick the .30 caliber but it's a remnant from our misled youth.

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