Eric Cortina had the guy from Ammolytics on his podcast, and he's on the path of doing something similar with super duper high speed cameras to try and measure this "sine wave" and "whip" that everyone fantasizes about. IIRC he said he doubts a lot of the theory and believes what AB posted here, the majority of the movement comes from the recoil before muzzle exit. It will be interesting to see his results if he continues with it, but the idea of "nodes" or "tuning" a load so that the bullet exits at the same point of it's cycle using "OBT" or something, with a bullet doing 3,000fps avg and as ES of 40, cracks me up. Manage recoil, shoot better.Not that it wasn't obvious in the first place but AB just did a super slow mo of rifle recoil before the bullet leaves the barrel. The recoil was 0.057" before the bullet even exited the barrel (.30-06 Remington NDL with 180gr). It's their way of stressing how important consistent fundamentals are since the rifle is moving before the bullet leaves the barrel. I think they're also currently on a crusade to show that reloaders' concentration on "harmonics" and "nodes" is mostly woowoo bullcrap since they mentioned the barrel doesn't appear to visibly vibrate at all before the bullet exits. I don't really have an opinion on that part.