This what Winchester advertises:

AUTOCOMP is extremely fine in the 38 Super, 9mm, 45 ACP and 40 S&W race guns. It’s just the perfect burning speed to feed the compensators with a higher volume of gas. With AUTOCOMP competitors get off faster shots with minimal muzzle flash, it’s a winner.

I have not used it as of yet, have bought quite of bit of surplus 231, it will be a long time before I will need any pistol powder.