John Linebaugh

John Linebaugh is an American gunsmith from Cody, Wyoming, known for creating custom firearms. He is inventor of the .500 Linebaugh (invented 1986) and .475 Linebaugh (1988) cartridges. Gunwriter John Taffin, a big-bore enthusiast, describes Linebaugh as a "pioneer" in developing powerful sixguns.
Biography.
Linebaugh's early efforts in the 1970s produced revolvers made to handle much more powerful loadings of .45 Colt than standard firearms, and later expanded into creating his own cartridge designs. After inventing the .500 and .475 Linebaugh, he later created a variant of each cartridge, lengthened to 1.61 inches, and appended "Maximum" to their names. Linebaugh focused on developing cartridges which were compatible with standard-size revolvers, keeping them "old school" or "packable" rather than oversize.