A good propellant for loads that make "Major" in .38 Super, also. It was my impression that AA#7 was also a close approximation to W571. But then, what of the new W572? Is THAT anything other than some allegedly "New & Improved" version of W571 in which they've "stick a bolt through its neck and made it walk around" (apologies to Gene Wilder and Peter Boyle)?