One of the most powerful sporting rifle cartridges ever commercially produced. Drives a 750-grain bullet at 2,460 fps, generating over 10,000 ft-lbs of muzzle energy — roughly equivalent to a double-rifle in .600 Nitro Express. Recoil exceeds 170 ft-lbs.
Type: Rifle
Introduced: 1993, United States
Parent case: .577 Nitro Express 3"
Standardization: None
Bullet diameter: 0.585" (14.86 mm)
Case length: 3" (76.2 mm)
Overall length: 3.9" (99.06 mm)
Max pressure: 25,000 PSI
Rim type: Rimless
Primer: Large Rifle Magnum
Typical twist rate: 1:16
Muzzle velocity: 2460–2460 fps
Muzzle energy: 10077–10077 ft-lbs
Effective range: 150 yd
Common bullet weights: 750 gr
Primary use: Hunting
Production status: Active
Also known as: .577 T-Rex · A-Square .577 Tyrannosaur
History: Developed in 1993 by Art Alphin of A-Square for hunters pursuing dangerous African game with a bolt-action rifle. The name Tyrannosaur captures the cartridge's extreme power. It was designed to replicate double-rifle stopping power in a magazine rifle format, giving African PH backup protection without the premium cost of a double. Recoil is violent even with a muzzle brake — earning it a…
Notable firearms: A-Square Hannibal, Custom bolt-actions on Magnum Mauser actions
Similar cartridges: .600 NE, .585 Nyati, .500 NE