Seems to me the .40/90 Sharps Straight and .40/70 both had close to a .457" base dia. as .30/40 Krag (stretched) could be used. Same with .303 brass having a .457" base. I have seen guys say they had .452" base, but that is incorrect, afaik. Speer manual notes the .30/40 Krag case is .461" at the rim\s front, but Hornady manual notes a spot just in front of the rim at .457".