For what it is worth Elkhunter11 is right different powders at the same pressure give different velocities. Salvee your equal resitance is the barrel not the powders pressure curve. When the big companies test loads it is with the same rifle for all the data per bullet weight. Some companies may change primers while gathering their data but very few.
I too thought it was a brass or case weakness problem with the 6.5x55 but I think it is a few weak rifles. Although I have an old Speer manual that has hotter loads in it for the military rifles than the newer Nosler manual has for modern rifles.
I like the 6.5x55 and wish I knew what pressure the modern rifles are to be loaded to. It should by all rights shoot faster than the 260 Rem and 6.5 CM but load data says no. If we look at that though the 270 Win is loaded to 65000 PSI and the 280 Rem only to 60000 PSI. Why they are loaded in the same kinds of rifles on the same case design.
|