Re: .260 round and competition.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sig685</div><div class="ubbcode-body">
I always believed the wind to have the same effect on bullets of the same sectional density. The BC (which is governed by the SD but also by the shape of the bullet) simply allowed the bullet to not lose speed as quickly as a bullet with a lesser BC value. The consequence of this is that a higher BC bullet would retain more of its initial velocity longer and since velocity has a time factor, the faster the bullet goes the less time it is in flight. The less time the bullet spends in the wind, the less the wind can deflect it. So I always thought that it was not so much that a high BC bullet slips through the wind undisturbed, but rather that it's simply not in the wind long enough to be disturbed.</div></div>
To my understanding, and I'm not a ballistician, this is wrong. The amount of wind drift isn't just affected by the time of flight, but also by the BC of the bullet. IIRC, the amount of wind drift is calculated by the difference between flight time in a vacuum and actual flight time- how much the bullet has been slowed down by the air. So, a higher BC bullet can have less wind drift than a lower BC bullet, even if it has a longer flight time.
To illustrate, I just ran two bullets through through JBM software and played with the velocities until they had identical flight times. In .308, a 168 SMK at 2711 fps and a 190 SMK at 2500 fps both had a flight time of 1.768 seconds at 1000 yards with the default environmental conditions. The 168 SMK had 11.2 MOA of wind drift, the 190 had 9.6. Same flight time and caliber, but different wind drift.
