Unfortunately I have no method of measuring direct pressure or temperature of the expanding gas. I was hoping this would prove to be a good (or at least moderately acceptable) method to estimate pressures of .38 LC from .38 special load data. As of late, I've been loading MBC Cowboy #2 .38 spl with AutoComp, and I like the results. I'd like to load some .38 LCs with it, but I can't find any load data for that particular cartridge. I figure that the min AutoComp load for .38 special (7300 PSI/7.7 inch barrel) would be plenty low in a LC case, but I'd just like know approximately what the pressure would be in the LC case. Boyle's Law gives about 9300 PSI.