Rifle · Wildcat
6 BRA
The 6mm BR with a 40-degree Ackley shoulder, gaining slightly more case capacity and more consistent fire-forming than the parent 6mm BR.
- Caliber
- 0.2429″ · 6.17 mm
- Introduced
- 1978
- Case
- Rimless
- Parent
- 6mm BR Norma
- Primary use
- target, competition
- Status
- Active
- Introduced
- 1978
- Type
- Rifle
- Origin
- United States
- Inventor
- Benchrest community
- Manufacturer
- David Tubb / various
- Standard
- Wildcat
- Status
- Active
- Availability
- Specialty
- Case capacity
- 37 gr H₂O
- Twist (typical)
- 1:7.5
- Primer
- Small Rifle
- Case type
- Rimless
- Max pressure
- 55,000 psi
- Eff. range
- 1000 yd
- Recoil
- 6.5–10 ft·lb
Ballistics
Published velocity/energy data isn't available for 6 BRA. Parent case: 6mm BR Norma.
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 · approximate| Measure | mm | in | ✓ |
|---|---|---|---|
| Bullet ⌀ | 6.17 | 0.243 | · |
| Neck ⌀ | 6.88 | 0.271 | · |
| Shoulder ⌀ | 11.68 | 0.460 | ~ |
| Shoulder angle | 40° | — | · |
| Base ⌀ | 11.96 | 0.471 | · |
| Rim ⌀ | 12.01 | 0.473 | · |
| Belt ⌀ | n/a | ||
| Rim thickness | 1.37 | 0.054 | · |
| Neck length | 8.18 | 0.322 | ≈ |
| Case length | 38.86 | 1.530 | ~ |
| Overall length | 68.58 | 2.700 | ~ |
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. 6 BRA is highlighted below.
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.
Lineage
Connected reference
History
As the 6mm BR Norma gained traction in F-Class and benchrest competition, shooters began fire-forming the brass to an improved shoulder for marginally better performance and brass life. The 6 BRA became a well-established benchrest cartridge in its own right and is recognized as the developmental ancestor of the 6mm Dasher.
FAQs
- What twist rate does 6 BRA use?
- 6 BRA typically uses a 1:7.5 twist rate.
- What bullet diameter is 6 BRA?
- 6 BRA uses a 0.2429″ (6.17 mm) diameter bullet.
- Is 6 BRA still in production?
- 6 BRA is active; typical availability is specialty.
- What is 6 BRA used for?
- 6 BRA is primarily used for target, competition.
- What is 6 BRA based on?
- 6 BRA is derived from the 6mm BR Norma case.
Sources & provenance
- Standard SAAMI — SAAMI cartridge & chamber drawing — 6 BRA archived
- Standard SAAMI — ANSI/SAAMI Z299 — Cartridge & Chamber Drawings archived
Data & sources. Specs compiled from the Lindcott Armory reference; availability counted from 20 live factory loads; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →