As one who is relatively new to loading for handguns.....and in particular 9mm......still struggling to wrap my head around the wide open range of powders used. On the Hodgdon burn chart with 160 powders listed, load data can be found for most in the first 50 with at least a dozen more powders used in 9mm not even on the chart.....so a wide open array of powders to chose from. Fast to slower......just as mentioned here, with A2, A5, A7 and A9. Clearly all can be used, so when is one better than the other? I often see the fast powders mentioned for "target" or "plinking loads", but some load data gets many of them up to same velocity as the "full power" loads. Do the fast powders give you a light powder puff recoil when used with light for caliber bullets? Slow powders for heavy bullets at high velocity?
A2, A5, A7, A9?
From large flakes alone (not counting BE-86, Power Pistol, Sport Pistol, etc), Alliant has Red Dot (and Promo), e3, American Select, Green Dot, Unique, Herco, Blue Dot? There is 9mm load data for all of them. So when and where? It's like going to the store and finding 15 choices for bottled water or table salt.