I would say your on the right track .I would beleive the factory powder would be win. or hodgen , pull a factory bullet dump the powder, than you will know if you are looking for a ball powder or other and weigh, it cross referance it with some listed loads, that give you a better idea of what powder you are lookin for
I would chrono a couple factory rounds too and see what velocty you are getting and see if you duplicte that with powder charge , refering to load mauals will narrow this down too. if you get the type (ball, extruded ect.) and charge weight.
