Rifle · Wildcat
.338 Razorback
Ultra-efficient subsonic AR-15 wildcat: a 10mm Auto pistol case reformed to .338, driving a ~300gr bullet at ~1,000 fps..
- Caliber
- 0.338″ · 8.585 mm
- Introduced
- 2022
- Case
- Rimless
- Parent
- 10mm Auto
- Primary use
- Hunting, Big Game
- Status
- Limited
- Introduced
- 2022
- Type
- Rifle
- Origin
- United States
- Inventor
- Unknown / wildcat
- Manufacturer
- Handloaded only (wildcat; no factory ammunition)
- Standard
- Wildcat
- Status
- Limited
- Availability
- Handload Only
- Case capacity
- 20.3 gr H₂O
- Twist (typical)
- 1:10
- Primer
- Large Rifle
- Case type
- Rimless
- Max pressure
- 60,000 psi, SAAMI transducer
- Eff. range
- 150 yd
- Max range
- 4500 yd
- Recoil
- 9.7–21.9 ft·lb
Ballistics
Velocity only, no drag model: no published ballistic coefficient is on file for .338 Razorback, 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
- 10mm Auto
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.
SAAMI · approximate| Measure | mm | in | ✓ |
|---|---|---|---|
| Bullet ⌀ | 8.59 | 0.338 | ~ |
| Neck ⌀ | 9.43 | 0.371 | |
| Shoulder ⌀ | 10.23 | 0.403 | |
| Shoulder angle | 23° | — | |
| Base ⌀ | 10.79 | 0.425 | ~ |
| Rim ⌀ | 10.79 | 0.425 | ~ |
| Belt ⌀ | n/a | ||
| Rim thickness | 1.40 | 0.055 | ~ |
| Neck length | 8.86 | 0.349 | |
| Case length | 25.20 | 0.992 | ~ |
| Overall length | 55.88 | 2.200 | ~ |
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 Razorback is highlighted below.
Missing a dimension for .338 Razorback? 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.
Lineage
Connected reference
History
Introduced in the early 2020s by Underwood Ammo (credited to Jeff Mager); a reformed 10mm Auto case for suppressed subsonic AR-15 use. (DB year 2005 was incorrect.)
FAQs
- What twist rate does .338 Razorback use?
- .338 Razorback typically uses a 1:10 twist rate.
- What bullet diameter is .338 Razorback?
- .338 Razorback uses a 0.338″ (8.585 mm) diameter bullet.
- Is .338 Razorback still in production?
- .338 Razorback is limited; typical availability is handload only.
- What is .338 Razorback used for?
- .338 Razorback is primarily used for hunting, big game.
- What is .338 Razorback based on?
- .338 Razorback is derived from the 10mm Auto 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 →
