I have a physics degree, I'm now retired and have taken up long range shooting as a hobby. When shooting at 600 yards, my spotters have noticed the contrail of my bullet follows a helical trajectory near the target. I shoot a 243 (6mm), 105 grain target bullet made by Berger at a muzzle velocity of about 3200 fps. When I spot for other good shooters (shooting a minute of arc or better at 600 yards), I notice their contrails show a straight path to the target, the only curvature of the path is an arc due to bullet drop. There are all kinds of shooting experts whose expertise seems to be more legendary according to the length of their drawl. They have all kinds of seat of the pants theories, but I was wondering if anyone has ever studied the physics and figured out why this happens and how to correct it. I load my own target ammo, so it's relatively easy to make adjustments.