[redhawk41]

Tom. thank you, that makes perfect sense.
a larger bore diameter will require a larger volume of gas to generate the same pressure as a smaller diameter bore. a fast powder in a large bore will generate that volume of gas in a shorter time period to generate the desired pressure. a slow powder will generate the gas volume over a longer time period which will not generate as much pressure.
firearms fascinate me because they are simple, yet so complex.
and one more reason why load data cannot be "interpreted".