The 3 things that affect a powder burn are: case capacity, bullet weight, and bore size. The case has a volume to contain the pressure initially, then the bullet has to start down the bore--hence the weight factor; then the bore size adds to the total volume, a smaller bore adds volume slower. This is why something like a .243 will use the same powders as a .300 WB--the ratios are similar.
Manufactorers will use powder we can't get, and mix powders to get their performance curve, they can afford it because they use thousands of pounds. I know of only one handloader who would blend powders to what he wanted. I don't know if he really outdid anyone else, but he was an OLD man with all his fingers and both eyes.
It is perplexing to find data that does not list newer powders. Sometimes it is something like my .300 Savage that it isn't worth the time to work up loads for 4007 or such, although it should work. Others it is unsuitable for.
Finally, at times the next increment of powder will work most of the time, but an odd spike will occur on occasion that sets the top limit.
The other thing is the similar names; ie; H4831 and IMR 4831
