Wildcat · Wildcat
6mm International
Historically important 6 mm competition wildcat based on the .250 Savage case (Walker version)..
- Caliber
- 0.243″ · 6.172 mm
- Introduced
- 1957
- Case
- Rimless
- Parent
- .250 Savage
- Primary use
- Competition, Target
- Status
- Wildcat
- Introduced
- 1957
- Type
- Wildcat
- Origin
- United States
- Inventor
- Mike Walker
- Standard
- Wildcat
- Status
- Wildcat
- Availability
- Handload Only
- Primer
- Large Rifle
- Case type
- Rimless
- Eff. range
- 300 yd
Ballistics
Velocity only, no drag model: no published ballistic coefficient is on file for 6mm International, 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
- .250 Savage
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.
reloading data · secondary source| Measure | mm | in | ✓ |
|---|---|---|---|
| Bullet ⌀ | 6.17 | 0.243 | · |
| Neck ⌀ | 6.91 | 0.272 | · |
| Shoulder ⌀ | 10.62 | 0.418 | · |
| Shoulder angle | 26° | — | · |
| Base ⌀ | 11.89 | 0.468 | · |
| Rim ⌀ | 12.01 | 0.473 | · |
| Belt ⌀ | n/a | ||
| Rim thickness | 1.22 | 0.048 | · |
| Neck length | 9.68 | 0.381 | ≈ |
| Case length | 48.56 | 1.912 | · |
| Overall length | 62.23 | 2.450 | ~ |
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. 6mm International is highlighted below.
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
Late-1950s 300m target wildcat by Remington engineer Mike Walker; tested by the U.S. Army AMU 1957–58. A separate Donaldson version also exists.
FAQs
- What bullet diameter is 6mm International?
- 6mm International uses a 0.243″ (6.172 mm) diameter bullet.
- Is 6mm International still in production?
- 6mm International is wildcat; typical availability is handload only.
- What is 6mm International used for?
- 6mm International is primarily used for competition, target.
- What is 6mm International based on?
- 6mm International is derived from the .250 Savage case.
Sources & provenance
- Manufacturer Sierra Bullets — 6mm International load data · bullet ⌀, grain weights, velocity archived
- Secondary AccurateReloading forums — 6mm/250 Savage (6mm International) load data thread · velocity archived
Data & sources. Specs compiled from the Lindcott Armory reference; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →