Following World War II, independent gunsmiths in the United States began exploring the ballistic possibilities of military surplus IMR 4831 powder salvaged from Oerlikon 20mm cannon cartridges and marketed by Hodgdon Powder Company.Hagel, Bob Propellant Profiles (Volume 1) 1982 Wolfe Publishing Company , pp.113-114 The long range ballistics of wildcat cartridges resulted in commercial availability of the 7×61mm Sharpe & Hart in 1953, and the 7mm Remington Magnum in 1962.Hornady, J. W. Hornady Handbook (1967) Hornady Manufacturing Company pp.155&158 The .275 H&H had been a cartridge ahead of its time.
