these two powders sit side by side on my burn rate chart, but I have little to no experience with them. are they interchangeable? can the same load data for one, be substituted for the other safely? or are we talking apples and oranges here? are they close enough that if you drop back 15% you can use the data and work up a load? I am asking because I have a load that calls for H4198 and all I have is IMR4198.