Rifle · Obsolete / Non-standard
.500 A-Square
A-Square's powerful proprietary cartridge using a rebated rimless case.
- Caliber
- 0.51″ · 12.954 mm
- Introduced
- 1978
- Case
- Rimless
- Parent
- .460 Weatherby Magnum
- Primary use
- Hunting
- Status
- Discontinued
- Introduced
- 1978
- Type
- Rifle
- Origin
- United States
- Inventor
- Art Alphin / A-Square
- Manufacturer
- A-Square
- Standard
- Obsolete / Non-standard
- Status
- Discontinued
- Availability
- Collector
- Case capacity
- 141.45 gr H₂O
- Twist (typical)
- 1:10
- Primer
- Boxer Large Rifle
- Case type
- Rimless
- Max pressure
- 63,860 psi, SAAMI transducer
- Eff. range
- 100 yd
- Max range
- 4800 yd
- Recoil
- 140.5–160.3 ft·lb
Ballistics
Published velocity/energy data isn't available for .500 A-Square — an obsolete/collector cartridge. Parent case: .460 Weatherby Magnum.
Performance
Dimensionscase measurements · scale drawing · size vs familiar rounds
Case dimensions — the scale drawing at the top of the page is built from these.
Wikipedia · approximate| Measure | mm | in | ✓ |
|---|---|---|---|
| Bullet ⌀ | 12.95 | 0.510 | · |
| Neck ⌀ | 13.61 | 0.536 | · |
| Shoulder ⌀ | 14.43 | 0.568 | · |
| Shoulder angle | 23° | — | |
| Base ⌀ | 14.78 | 0.582 | · |
| Rim ⌀ | 14.71 | 0.579 | · |
| Belt ⌀ | 15.32 | 0.603 | ~ |
| Rim thickness | 1.60 | 0.063 | ~ |
| Neck length | 13.37 | 0.526 | |
| Case length | 73.66 | 2.900 | · |
| Overall length | 95.00 | 3.740 | · |
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. .500 A-Square is highlighted below.
Missing a dimension for .500 A-Square? Some case measurements aren't in a published SAAMI/CIP drawing yet. Have a factory or reamer print? Send it → — verified hard-to-find data earns a free Lindcott sticker.
Factory loads
Being verified
Advertised FPS, energy, and BC are withheld until loads clear verification.
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 .500 A-Square
Lineage
History
Developed by A-Square company in the 1980s using a rebated rimless case design. Intended as an alternative to .505 Gibbs for ultra-heavy dangerous game. The cartridge fires 600-grain bullets at ~2,200 fps, generating extreme recoil. A-Square's demise limited commercial adoption; primarily a custom market cartridge.
FAQs
- What twist rate does .500 A-Square use?
- .500 A-Square typically uses a 1:10 twist rate.
- What bullet diameter is .500 A-Square?
- .500 A-Square uses a 0.51″ (12.954 mm) diameter bullet.
- Is .500 A-Square still in production?
- .500 A-Square is discontinued; typical availability is collector.
- What is .500 A-Square used for?
- .500 A-Square is primarily used for hunting.
- What is .500 A-Square based on?
- .500 A-Square is derived from the .460 Weatherby Magnum case.
Sources & provenance
Data & sources. Specs compiled from the Lindcott Armory reference; availability counted from 17 live factory loads; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →
