Reloading manuals give reloading data with many different FMJ bullets- RN, hollow point, JSP, TMJ, Speer GDHP, Hornady XTP, FMJ Match, etc. What do you do when the bullets you are using are different from those use in the Reloading Manual? For example, you have RN FMJ, and the load described is for GDHP's? Or you have Montana Gold TMJ and the Load data is for Hornady XTP bullets? To what extent are FMJ bullets different or the same in deciding on a correct powder charge? Thank you.