Rifle · Wildcat
.338-06 A-Square
A classic wildcatter's answer to the .30-06 — neck it up to .338 for a powerful all-around hunting round that works in any standard .30-06 action..
- Caliber
- 0.338″ · 8.585 mm
- Introduced
- 1944
- Case
- Rimless
- Parent
- .30-06 Springfield
- Primary use
- Hunting
- Status
- Limited
- Introduced
- 1944
- Type
- Rifle
- Origin
- United States
- Inventor
- Charles O'Neil / Elmer Keith / Don Hopkins
- Manufacturer
- A-Square Company
- Standard
- Wildcat
- Status
- Limited
- Availability
- Scarce
- Case capacity
- 71 gr H₂O
- Twist (typical)
- 1:10
- Primer
- Large Rifle
- Case type
- Rimless
- Max pressure
- 60,000 psi
- Eff. range
- 400 yd
- Max range
- 1500 yd
- Recoil
- 15–22 ft·lb
Ballistics
Published velocity/energy data isn't available for .338-06 A-Square. Parent case: .30-06 Springfield.
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 · secondary source| Measure | mm | in | ✓ |
|---|---|---|---|
| Bullet ⌀ | 8.59 | 0.338 | · |
| Neck ⌀ | 9.37 | 0.369 | · |
| Shoulder ⌀ | 11.20 | 0.441 | · |
| Shoulder angle | 17.5° | — | · |
| Base ⌀ | 11.98 | 0.472 | · |
| Rim ⌀ | 12.01 | 0.473 | · |
| Belt ⌀ | n/a | ||
| Rim thickness | 1.24 | 0.049 | ~ |
| Neck length | 10.97 | 0.432 | ≈ |
| Case length | 63.35 | 2.494 | · |
| Overall length | 85.60 | 3.370 | · |
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. .338-06 A-Square is highlighted below.
Factory loads
Being verified
Advertised FPS, energy, and BC are withheld until loads clear verification.
Suitable powders
7 reloading powders listed for .338-06 A-Square, fastest to slowest. Cross-reference in the finder →
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.
Lineage
Connected reference
History
Developed by Charles O'Neil, Elmer Keith, and Don Hopkins in 1944 — the same triumvirate who created the .333 OKH and other classics. A-Square later commercialized it. The .338-06 sits between the .338 Federal and .338 Winchester Magnum in performance, offering more power than the Federal with less recoil than the Win Mag. SAAMI never standardized it despite A-Square's efforts. Nosler and several custom loaders still produce ammunition. It's the cartridge .338 enthusiasts build their first wildcat rifle around.
FAQs
- What twist rate does .338-06 A-Square use?
- .338-06 A-Square typically uses a 1:10 twist rate.
- What bullet diameter is .338-06 A-Square?
- .338-06 A-Square uses a 0.338″ (8.585 mm) diameter bullet.
- Is .338-06 A-Square still in production?
- .338-06 A-Square is limited; typical availability is scarce.
- What is .338-06 A-Square used for?
- .338-06 A-Square is primarily used for hunting.
- What is .338-06 A-Square based on?
- .338-06 A-Square is derived from the .30-06 Springfield case.
- What are the best powders for .338-06 A-Square?
- Reloading powders commonly listed for .338-06 A-Square include IMR 3031, 203-B, Norma 202, H380, among 7 suitable options.
Sources & provenance
Data & sources. Specs compiled from the Lindcott Armory reference; availability counted from 3 live factory loads; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →