The video is frustrating because while some of his content is great, he really needs to stay out of the “probably” business. Nearly all bullets have their CP (center of pressure) forward of their CG (center of gravity). Thus if you drop one from a height, it will tend to fall tail-first. Instead of resorting to “probably” he could have just tested this. A falling object seeks force equilibrium, not minimum drag. The minimum drag configuration is nose low. The forces-in-equilibrium configuration is the CG leading into the relative wind, the CP trailing directly behind it, and the CG-CP arm aligned with the relative wind. This is the equilibrium attitude. Keeping the bullet in its lowest-drag configuration means keeping the “pointy end” forward. This is done with spin in a CP-forward projectile, and with fins in a CP-rearward projectile.
A bullet spinning in flight is experiencing extraordinary gyroscopic forces. A typical bullet is spinning in the range of 150,000 to 300,000 RPM. Like all objects under gyroscopic influence, that means a bullet in flight has two properties:
Rigidity in space. The bullet resists perturbation along its longitudinal access. This is good, it keeps the bullet from flipping around and flying tail-first. But it also means the bullet’s orientation is called “intractable”… It tends to stay in the orientation that it left the barrel, and as the bullet’s path starts to descend, the bullet is starting to fly more and more “nose high” compared to the relative wind. This creates upward pressure on the CP of the bullet, forward of the CG. So the nose should go up, right? Actually, no. This is because of the other property of gyroscopes…
Precession 90 degrees in the direction of spin. The gyroscopic force translates that nose-up, tail-down torque on the fast-spinning bullet into a nose-right yaw on the bullet because most rifling is to the right (clockwise ) from the shooter’s perspective. There will be a tiny Magnus force pulling the bullet to the left and a much larger gyroscopic force pulling the bullet to the right, called spin drift.
People try to simplify ballistics by applying intuition. But that intuition is almost always formed by a lifetime of observing things with “high-Magnus, low-spin drift” like a ball, or things with their CP behind their CG, like model rockets or arrows, in an effect called “weathervaning.” But that intuition is incorrect because most of us will never visibly observe an object in flight that has a CP forward of the CG, nor one that is traveling a long enough distance or time of flight while remaining in our view. I cannot hit a golf ball far enough for Coriolis to really matter. I can’t spiral a football with nearly enough spin for me to be able to observe spin intractability. And so our intuition about how a bullet flies will almost always end up wrong.
