A wildcat cartridge, often shortened to wildcat, is a custom-made cartridge for which ammunition and/or firearms are not mass-produced. These cartridges are often created as experimental variants to optimize a certain ballistic performance characteristic of an existing commercial cartridge, or may merely be intended as novelty items.
The .600 Nitro Express (15.7x76mmR) is a large bore Nitro Express rifle cartridge developed by W.J. Jeffery & Co for the purpose of hunting large game.
The .577 Nitro Express is a large-bore centerfire rifle cartridge designed for the purpose of hunting large game such as elephant. This cartridge is used almost exclusively in single-shot and double express rifles for hunting in the Tropics or hot climates in general and is a cartridge associated with the golden age of African safaris and Indian shikars.
The .400/350 Nitro Express, also known at the .400/350 Nitro Rigby, is a medium bore rifle cartridge developed by John Rigby & Company.
The .303 is an arguably obsolete but capable medium bore rifle cartridge.
The .255 Jeffery Rook / 6.5x29mmR, also known as the .255 Jeffery Rook Rifle, is an obsolete small bore intermediate firearm cartridge.
The .400 Purdey, also known as the .400 3-inch Straight and .400 Purdey Light Express 3-inch, is an obsolete rifle cartridge developed by James Purdey & Sons.
The .300 Sherwood / 7.6x39mmR, also known as the .300 Extra Long and the .300 Westley, is an obsolete intermediate centerfire rifle cartridge developed by Westley Richards.
The .300 Rook / 7.6x30mmR, also known as the .295 Rook, is an obsolete intermediate centerfire rifle cartridge.
The .297/250 Rook / 6.4x21mmR is an obsolete centerfire rifle cartridge developed by Holland & Holland.
The .220 Rook / 5.7x18mmR, also known as the .220 Long Centrefire, is an obsolete British centerfire rifle cartridge.
The .360 No. 5 Rook / 9.2x27mmR is an obsolete centerfire rifle cartridge.
The .400/360 Nitro Express cartridges are a number of very similar, but not interchangeable, centerfire rifle cartridges developed by James Purdey & Sons, William Evans, Westley Richards and Fraser of Edinburgh, all at the beginning of the 20th century.
The .360 No. 2 Nitro Express is a centerfire rifle cartridge developed by Eley Brothers and introduced in 1905.
The .500/450 No. 1 Black Powder Express, known in its day as the .500/450 No. 1 Express, was a centerfire rifle cartridge developed by Westley Richards and introduced in the late 1870s.
The .461 No 1 Gibbs and the .461 No 2 Gibbs are two obsolete proprietary rifle cartridges developed in 19th century Britain.
The .280 Flanged Nitro Express, also known as the .280 Lancaster, is an obsolete rimmed bottleneck centerfire rifle cartridge developed by Charles Lancaster and introduced in 1906.
The .297/230 Morris Short and .297/230 Morris Long are two obsolete centerfire firearm cartridges developed as sub-caliber training rounds for the British Martini–Henry rifle.
The 6.5×57mm Mauser is a smokeless powder rimless bottlenecked centerfire rifle cartridge developed by Paul Mauser and introduced in 1893–94.
