Lindcott Armory 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
- Parent case
- .577 Nitro Express 3"
Representative trajectory — modeled from a single velocity input (no published BC for this cartridge yet).
Performance
Buy links open .577 Tyrannosaur ammunition at Rivertown Munitions.
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
In production — 4 active loads across 1 brand. Top 4 shown.
| Brand | Load | Grain | Bullet | FPS | ft·lb | BC |
|---|---|---|---|---|---|---|
| A-Square | Dead Tough | 750 | SP | 2,460 | 10,076 | — |
| A-Square | Dead Tough SP | 750 | Dead Tough SP | 2,460 | 10,076 | — |
| A-Square | Monolithic Solid FMJ | 750 | FMJ Solid | 2,460 | 10,076 | — |
| A-Square | Trophy Bonded | 750 | TBT | 2,460 | 10,076 | — |
Velocities are manufacturer-stated (test-barrel). Discontinued loads dimmed.
Reloading costestimate cost per round vs factory
Estimate your cost per round and how it compares to factory. Inputs are yours — nothing is stored.
Cost estimate only — not load data. Charge weight is your input; follow published manuals for safe charges.
Firearms chambered in .577 Tyrannosaur
2 models in the database chamber .577 Tyrannosaur. Browse all →
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 →