IMR: That has a heritage of quality, IMR powders are renowned for their outstanding effectiveness, especially in rifle calibers, offering trustworthy and reliable results. With vintage powders, I did take a look at some vintage loading manuals and found some dissimilarities in recommended load...possibly from your powder recipe transforming somewhat https://andykqusu.angelinsblog.com/32328833/how-much-you-need-to-expect-you-ll-pay-for-a-good-smokeless-powder