I read in Hornady's 9th edition that Jim Carmichael was involved in developing the .260 Remington. They should check the historical records. P.O. Ackley attributed the ".263 Express" to Ken Waters in the Handbook for Shooters & Reloaders, Vol. 1, p. 356 (pub. 1962). In Ken Waters' Notebook, p. 364, we read that Mr. Waters developed the cartridge (.308 necked to .264) in the mid-1950s.
