Yeah, I was reading that in my Sharpe book just the other day where a 146gr load with 2400 was in the 35,000 pressure range too! Now THAT is a very special 38 special load! WHHOOOO HHHOOOOOO!
I will throw my 2 cents worth about Bullseye and Unique being the same powder. If they are the same then the company would not package TWO different powders. If they were and I think they are not then why would Alliant take the extra time and expense to have two different ones. That is my take on this. It is my opinion only and not anyones else that I have talked to.
There are several ways to control burning rate. One is to offer more surface area, i.e. smaller granulation or more perforations. Another is to use different deterrents/coatings. The powder can be exactly the same and have two different burn rates by using those methods.