it's quite useful but it's not gospel. one thing I found that I know isn't right. is a 45.5 grain load of varget in a 308 with a 168 Barnes my gun yields 2740 with that load and it is a published load. but GRT says it's over 80,000 PSI.. which I'm pretty sure is not right even if you loaded it up in mil-spec brass I don't think you would get that high a PSI. but I haven't went through and done though water grain entry and all that for specific brass
