I once talked to a "tech" for a bullet co. about the variation in data between manuals. I was told that the data in their book was acually valiad for only one of their bullets listed in the weight given. If you notice, most manufactores list spitzers, boat tails, round nose, ect all under one weight. The data shown is for the bullet that produced the most pressure with the given powder charge, each bullet reacts differntly and the best they can do is give you a load that SHOULD be safe with all components shown. Every time you change a component from a differnt lot, to a differnt manufacture, to a differnt style from the same manufacture, to a differnt test bed (rifle) the pressure and velocity can and will change. How much or in which direction you can`t tell without testing. Always reduce and work up when changing a component - safty first.
