Introduced by British gunmaker George Gibbs in 1911, the 505 Gibbs has one of the largest cases that can be crammed into a magnum-sized action. Rim and base diameter are .6402-inch; case length 3.150 inches. The 505 Gibbs is legendary for its power, and was perhaps made most famous by Ernest Hemingway as the professional hunter's choice in "The Short, Happy Life of Francis Macomber." The 505 Gibbs was not loaded to as high pressure as the 500 Jeffery, so although its case is larger it is not quite as powerful, propelling a .505-inch 525-grain bullet at 2300 fps--but certainly powerful enough for anything that walks! Like the 500 Jeffery, it was uncommon back in the day, but has seen a resurgence today, with both new rifles and ammunition readily available. —
Craig Boddington