I have been using Shooter's World Auto Pistol and Ultimate Pistol for a little over a year and really like it. This past gun show I got some Shooter's World Blackout powder for the 300 BO and loaded around 40 rounds to see how it works. On the canister, it also lists "for magnum pistols" too. I am going to try in it the 44 Mag. Got to see what powder it compares with on the burn chart.