Win 571 is HS7. By the way, it is discontinued. I used it in 357 mag and 40SW and It is the only powder I've used that I can actually say I don't like. It sucked in fact. In 357 mag using max loads it barely exceeded 38spl velocities and burned filthy. The data was too light apparently. In 40 SW I got the same velocity as Bullseye and it is the only time I have ever gotten the "Glock Bulge". I was given a can of it and was glad when I used the last of it up.
It is probably better suited for your 9mm loads since they run at a higher pressure.
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"If you kill enough of them, they stop fighting."-General Curtis E. LeMay