This thread isn't a competition but Bart and Sweet (both very knowledgable guys) are sure competing or trying to one-up with theories of barrel vibration. Sure the barrels vibrate. We all know that. The OP knows that, but the info put forth on vibration is not going to help him at all. That's why I suggested that if we want to actually help the guy, who did request our assistance, we need to suggest something a bit more practical than detailed theories of barrel whip. Of course, that practical info is already in the various posts, and the OP may have already taken action to fix his problem. I hope that he'll eventually tell us what did fix the problem. I'd like to know.
And I most certainly agree that I've learned a ton of things on this forum. It's made me a better reloader and a better shot, and I don't think I've ever thanked anyone for the bits of info that have been extremely helpful.