Black powder express cartridge in .577 caliber with 2.5 inch case. Used in British single-shot and double rifles for large game. Shorter than the later Nitro Express 3 inch version.
Type: Rifle
Introduced: 1875, United Kingdom
Parent case: None
Standardization: Obsolete / Non-standard
Bullet diameter: 0.57" (14.48 mm)
Max pressure: 18,000 PSI
Rim type: Rimmed
Primer: Large Rifle
Typical twist rate: 1:20
Muzzle velocity: 1500–1700 fps
Muzzle energy: 2598–3597 ft-lbs
Effective range: 150 yd
Common bullet weights: 520, 560 gr
Primary use: hunting
Production status: Obsolete
Also known as: .577 Express 2.5" · 577 Express 2 1/2 inch
History: A British Express cartridge for large-bore double rifles, designed for medium dangerous game at close range. The 2.5-inch case held sufficient black powder for modest velocity; an early attempt to standardize British dangerous game ammunition before nitro express replaced all black powder designs.