This cartridge was developed by George Gibbs of Bristol in 1911 and originally intended for use in double rifles, but somewhere along the road he changed his mind and turned it into a rimless round for use in magazine rifles, for which there was a flourishing market. The .505 Gibbs is a highly specialized cartridge intended as an elephant stopper for hunters who prefer a magazine rifle for this purpose. It is one of the old English big bore cartridges, whose reputation far exceeds its actual use It was made famous by Ernest Hemingway in his short story “The Short Happy Life of Francis Macomber” and the famous John A. Hunter also preferred a .505 for hunting elephant.
Actually the first rifle of this caliber was finished by the Gibbs company in 1914, and the first world war delayed the production of further rifles until 1919. Accordingly it reached the African game fields at the very end of professional elephant hunting and never became widespread.
It is not only equal to but exceeds the power of its rimmed cousin, the .500 Nitro Express. In European nomenclature it would be called 12,8x80. A 525 grain bullet propelled at 2300 fps gives an awesome recoil and rifles necessarily have to be heavy to reduce this to a tolerable level.