Richard J. "Dick" Casull (/kə'sul/) was a Utah-born gunsmith and wildcat cartridge developer whose experiments with .45 Colt ammunition in the 1950s led to the creation of the .454 Casull cartridge. Casull’s passion were six-shooters, and he was determined to create a high velocity round for the .45 Colt. His goal was to achieve a muzzle velocity of 2,000 feet per second with Colt .45 rounds fired from a single-action Army-style revolver with a 7 ½ inch barrel. This proved impossible due to the tensile strength of the Colt .45 cylinder, so he set out to develop his own casing and bullet.
Casull began his career as a wildcat cartridge developer after having contact with Elmer Keith in the 1940s, an Idaho rancher, firearms enthusiast, and author. Keith was instrumental in the development of the first magnum revolver cartridge, the .357 Magnum, as well as the later .44 Magnum and .41 Magnum cartridges. Keith was instrumental in the development of various wildcat cartridges, a few of which were later adopted as factory rounds.
Casull also worked with Oregon-based gunsmith P.O. Ackley, the famous wildcat cartridge developer. Ackley developed a family of improved wildcat cartridges by rechambering extant firearms and fireforming the ammunition to decrease body taper and increase shoulder angle, resulting in a higher case capacity. Ackley improved not only standard cartridges but was the creator of the first .17 caliber (4.5 mm) centerfire cartridge. He developed the .450 Ackley Magnum (based on a .375 H&H Magnum case necked up to .458) and the .475 Ackley Magnum (based on a .375 H&H Magnum necked up to .475 (12 mm)).
Though he developed many wildcat cartridges for pistols and rifles, Casull is most famous for creating the .454 Casull cartridge in 1957 with Jack Fullmer. It was first announced in November 1959 by Guns & Ammo magazine. The basic design was a lengthened and structurally improved .45 Colt case. The wildcat cartridge finally went mainstream in 1997, when Ruger began chambering its Super Redhawk in this caliber. Taurus followed with the Raging Bull model in 1998 and the Taurus Raging Judge Magnum in 2010. Taurus also made a now-discontinued Rossi-branded R92 lever action carbine clone of the Winchester 1892 chambered for the .454 Casull. For brush hunting and wilderness packing, the Rossi R92 carbine .454 Casull offered optional magazine-tube loading and a recoil absorbing butt pad.