Rifle · Not SAAMI standardized · Not standardizedObsolete
.500 Auto Max
.500 Auto Max is a rimless straight-walled rifle cartridge of United States origin.
- Caliber
- 0.5″ · 12.7 mm
- Introduced
- 2018
- Case
- Rimless
- Parent
- .500 S&W Magnum
- Primary use
- Hunting
- Status
- Discontinued
- Obsolete
- Obsolete
- Introduced
- 2018
- Type
- Rifle
- Origin
- United States
- Inventor
- Greg Buchel (Big Horn Armory) with Buffalo Bore
- Manufacturer
- Big Horn Armory (AR500 rifle); Buffalo Bore
- Standard
- Not SAAMI standardized · Not standardized
- SAAMI
- Not SAAMI standardized
- Obsolete
- Obsolete
- Status
- Discontinued
- Availability
- Rare
- Case capacity
- 64.3 gr H₂O
- Twist (typical)
- 1:24
- Primer
- Large Rifle
- Case type
- Rimless
- Max pressure
- 60,000 psi, SAAMI transducer
- Eff. range
- 250 yd
- Max range
- 1250 yd
- Recoil
- 9.8–15.4 ft·lb
Ballistics
Velocity only, no drag model: no published ballistic coefficient is on file for .500 Auto Max, so this is the shape gravity alone gives the advertised velocity. Drag would steepen it. The tool below solves real loads through their published G1 or G7 model.
Open in Ballistic Compare- Parent case
- .500 S&W Magnum
Representative trajectory — modeled from a single velocity input (no published BC for this cartridge yet).
Dimensionscase measurements · scale drawing · size vs familiar rounds
Case dimensions — the scale drawing at the top of the page is built from these.
mixed/other · approximate| Measure | mm | in | ✓ |
|---|---|---|---|
| Bullet ⌀ | 12.70 | 0.500 | ✓ |
| Neck ⌀ | 13.38 | 0.527 | |
| Shoulder ⌀ | n/a | ||
| Shoulder angle | n/a | ||
| Base ⌀ | 13.36 | 0.526 | ✓ |
| Rim ⌀ | 13.40 | 0.528 | |
| Belt ⌀ | n/a | ||
| Rim thickness | 1.46 | 0.057 | |
| Neck length | n/a | ||
| Case length | 41.27 | 1.625 | ✓ |
| Overall length | 52.13 | 2.052 | |
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 Auto Max is highlighted below.
Missing a dimension for .500 Auto Max? 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.
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 Auto Max
Lineage
Connected reference
History
Introduced around 2018 by Greg Buchel (Big Horn Armory) with Buffalo Bore, derived from the .500 S&W Magnum.
FAQs
- What twist rate does .500 Auto Max use?
- .500 Auto Max typically uses a 1:24 twist rate.
- What bullet diameter is .500 Auto Max?
- .500 Auto Max uses a 0.5″ (12.7 mm) diameter bullet.
- Is .500 Auto Max still in production?
- .500 Auto Max is discontinued; typical availability is rare.
- What is .500 Auto Max used for?
- .500 Auto Max is primarily used for hunting.
- What is .500 Auto Max based on?
- .500 Auto Max is derived from the .500 S&W Magnum case.
Sources & provenance
Data & sources. Specs compiled from the Lindcott Armory reference; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →
