Rifle · Not SAAMI standardized
.577 Tyrannosaur
A.G.
- Caliber
- 0.585″ · 14.859 mm
- Introduced
- 1993
- Case
- Rimless
- Parent
- .577 Nitro Express 3"
- Primary use
- Hunting
- Status
- Active
- Introduced
- 1993
- Type
- Rifle
- Origin
- United States
- Inventor
- Art Alphin / A-Square
- Manufacturer
- A-Square, custom
- Standard
- Not SAAMI standardized
- Status
- Active
- Availability
- Rare
- Case capacity
- 250 gr H₂O
- Twist (typical)
- 1:16
- Primer
- Large Rifle Magnum
- Case type
- Rimless
- Max pressure
- 65,000 psi
- Eff. range
- 100 yd
- Max range
- 400 yd
- Recoil
- 75–100 ft·lb
Ballistics
Published velocity/energy data isn't available for .577 Tyrannosaur. Parent case: .577 Nitro Express 3".
Performance
Dimensionscase measurements · scale drawing · size vs familiar rounds
Case dimensions — the scale drawing at the top of the page is built from these.
SAAMI · approximate| Measure | mm | in | ✓ |
|---|---|---|---|
| Bullet ⌀ | 14.86 | 0.585 | · |
| Neck ⌀ | 15.58 | 0.614 | · |
| Shoulder ⌀ | 17.09 | 0.673 | · |
| Shoulder angle | 8.2° | — | ~ |
| Base ⌀ | 17.50 | 0.689 | · |
| Rim ⌀ | 17.48 | 0.688 | · |
| Belt ⌀ | n/a | ||
| Rim thickness | 1.60 | 0.063 | · |
| Neck length | 12.72 | 0.501 | ≈ |
| Case length | 75.95 | 2.990 | · |
| Overall length | 94.23 | 3.710 | · |
Size vs familiar rounds
Drawn at true 1:1 — every case is accurate relative to the others. Absolute size depends on your screen's pixel density, so measuring one against a real ruler may be off. .577 Tyrannosaur is highlighted below.
Factory loads
Being verified
Advertised FPS, energy, and BC are withheld until loads clear verification.
Reloading costestimate cost per round vs factory
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Firearms chambered in .577 Tyrannosaur
2 models in the database chamber .577 Tyrannosaur. Browse all →
Lineage
Connected reference
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 reputation as one of the most punishing sporting cartridges to shoot.
FAQs
- What twist rate does .577 Tyrannosaur use?
- .577 Tyrannosaur typically uses a 1:16 twist rate.
- What bullet diameter is .577 Tyrannosaur?
- .577 Tyrannosaur uses a 0.585″ (14.859 mm) diameter bullet.
- Is .577 Tyrannosaur still in production?
- .577 Tyrannosaur is active; typical availability is rare.
- What is .577 Tyrannosaur used for?
- .577 Tyrannosaur is primarily used for hunting.
- What is .577 Tyrannosaur based on?
- .577 Tyrannosaur is derived from the .577 Nitro Express 3" case.
Sources & provenance
Data & sources. Specs compiled from the Lindcott Armory reference; availability counted from 4 live factory loads; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →