I was curious becuase I purchased an after market match barrel for a pistol of mine and not only were the rifling different sizes but they spun in the opposite directions. That's what got me thinking about it and why I wondered if there was a differance or if there was some kind of standard that the different brands use. Your test results would seem to indicate there must be at least some kind of uniform theory any ways. Thanks for the test comparison it was very thought provoking.