i think the .303 brit cartridge is the poster child for case-head separation...the brits didn't factor reloading into their war plans, it seems.
i learned at the t/c contender school of reloading...treat all cartridges like rimless whether they have a rim or not, so...i expand the necks of bottle-neck brass a few calibers, then size until they just chamber. after firing, i segregate for a particular firearm. after the initial firing, my brass is neck-sized, ensuring long-life.
budman
ignorance is fixable, stupidity is forever...