Think of this powder as IMR 4064 that has been updated to version 2.0. It is not sensitive to temperature changes, and has the de-coppering agent that the Hodgdon CFE powders have, but unlike IMR 4064 it has a nitroglycerin content of 10%. I have used it as a substitute for older loading data using IMR4064 grain for grain and it has worked well. With equivalent charges of both powders 4166 will deliver 10-20fps more velocity. On the Powder Burn Rate charts it is just 1 position faster than IMR4064. I use it for 8x52R Siamese Type 66 Mauser and 8x57 Mauser along with the 9.3x57 Mauser. I think the extra kick from the Nitroglycerin makes it burn a little cleaner also.