I know powder burn charts are to be used as a "loose" guide only. 3031 is shown as a fairly fast powder for rifles. I have tried to use it in a 6BR and 68 grain bullets, but the velocity just isn't there. Other slower powders do fine and never fill the case. I can't get enough 3031 in the case to get anywhere near the same velocities. Maybe it works in more straight walled cases, but not in the BR.