I started the thread about what's the difference in BPs. Lots of great info. But I still don't see the equation of definition of the differences to the performance. I come from a long history of smokeless reloading where nuance is highly regulated. Now with my own creations of BP I want to formulate some style of empiricism. I was reading about how they used to test BP prior to purchase. Basicly an under powered mortar. A static amount of powder had to propel what looked like 12" cannon ball so many feet in order to be viable for purchase. I'm looking for a device that "we" could agree would afford the same variables except the powder being used. Or said differently, A simple device that any of us could make or have to determine the strength of the BP where the only variable would be the BP being used. Or maybe I've got too much time on my hands. [Sorry that there is no prize if you have the winning idea.]