I have had SOME experience with Lil'gun. I think you need to have the case full/near full for it to perform properly. I am not sure if it is position sensitive or pressures get erratic when not full. It seems to be THE powder in 22 Hornet, but I have not found it to be the best in a 221 Fire Ball. I found that IMR 4198 and Reloader 7 to perform better. I have not done a lot of shooting with the 221 Fire Ball, but it does not fill the case, while the Reloader 7 and IMR 4198 come a lot closer. When you put in the recommended amount into your case (41 Mag) and if you get a near full case, I think you will get good performance out of it. If it does not fill the case or near full, then you may get erratic results. Just my 2 cents.