anyone ever tried mixing two powders to get a desired burn rate
It has been done. But, is generally viewed as smart as playing Russian Roulette. For almost all hand loaders, there is no compelling reason do do such.
Sometimes you get what you pay for, sometimes you only pay more for what you get.
Three shots are not a "group"...they are a "few".
If the Bible is the literal, infallible, unerring word of God...where are all those witches I am supposed to kill? (Exodus 22:18)