Thanks for the input Boots ! I've heard about the .004" variation but have never found any concrete evidence to verify. My Hornady #7 shows a cartridge drawing for both the 257 Robts & the RCBS version of the "improved" cartridge ( 28 degree). These drawings show the improved version being .005" shorter from base to shoulder/neck........... I probably need to get a copy of P.O. Ackleys' book for future reference. Your point is well taken. Dale