Transitional British Nitro Express cartridge bridging the .577 and .600 NE, used in early high-power double rifles.
Type: Rifle
Introduced: 1900, United Kingdom
Parent case: .600 NE (necked)
Standardization: Proprietary
Bullet diameter: 0.585" (14.86 mm)
Rim type: Rimmed
Primer: Boxer Large Rifle
Production status: Discontinued
Also known as: .600/577 NE · 600/577 Nitro Express
History: An early transitional cartridge from the development period of Nitro Express cartridges, the .600/577 NE used the enormous .600 NE case necked down to .577 caliber. It predates the standardization of the .600 NE as the definitive large-bore Nitro Express and is rare; encountered mainly in early 20th-century double rifles.