I just wanted to post this, as I had never really heard much about this powder till I just tried it myself. I have a S&W M686 6" in .357 Mag, and a S&W M629 4" in .44 Mag. Normally, when I buy powder for my magnum pistol loads, I usually use Alliant 2400, and when I can't find it, H-110, N-110, or W-296 is usually backup... Well, it seems our "elected official" has everyone scared to death, and people are buying up everything they can find. All of the shops I buy powder from within a 2 hour raduis were all out of the aforementioned powders. Well, I started looking through my burn rate charts looking for a reasonable alternative, and noticed that one store had several pounds of AA-4100 in stock, and according to my burn rate charts, it is usually listed as a little faster than 2400, but a tad slower than H110. Accurate Arms describes it as being slightly slower than AA No.9, and that No.9 load data can be used for 4100, while increasing 3% for the slower burning 4100. I bought this, and loaded a hundred rounds in .357, varying charges and using 158gr. Hornady XTPs and 125gr. Winchester JHPs. WOW! My 686 grouped some of the best groups it's ever shot, and I've even increased the load to match my top velocities with 2400 and 110, and getting better groups! Also, I'm not having to use magnum primers either, as I did with H-110 and W-296. I've not had a chance to test my .44 Mag loads yet, I've got them ready to go with 240gr. JHPs. I'll post back when I get the results. All in all, I am going to stick with this powder completely- at least for my .357 Magnum loads! And here's the best part - at my shop, 4100 is about $6 cheaper per pound than H-110 and $9 cheaper than N-110!