Rifle · SAAMI
.284 Winchester
Short-action 7mm cartridge with a rebated rim, fitting a .473" bolt face despite a larger .500" base.
- Caliber
- 0.2839″ · 7.21 mm
- Introduced
- 1963
- Case
- Rebated
- Primary use
- Hunting, Target, Competition
- Status
- Active
- Introduced
- 1963
- Type
- Rifle
- Origin
- United States
- Inventor
- Winchester
- Manufacturer
- Winchester Ammunition
- Standard
- SAAMI
- Status
- Active
- Availability
- Limited
- Case capacity
- 66 gr H₂O
- Twist (typical)
- 1:10
- Primer
- Large Rifle
- Case type
- Rebated
- Max pressure
- 56,000 psi
- Eff. range
- 500 yd
- Max range
- 1200 yd
- Recoil
- 12–16 ft·lb
Introduced by Winchester Ammunition
Ballistics
Published velocity/energy data isn't available for .284 Winchester.
Performance
Dimensionscase measurements · scale drawing · size vs familiar rounds
Case dimensions — the scale drawing at the top of the page is built from these.
CIP TDCC · verified| Measure | mm | in | ✓ |
|---|---|---|---|
| Bullet ⌀ | 7.21 | 0.284 | ✓ |
| Neck ⌀ | 8.13 | 0.320 | ✓ |
| Shoulder ⌀ | 12.06 | 0.475 | ✓ |
| Shoulder angle | 35° | — | ✓ |
| Base ⌀ | 12.72 | 0.501 | ✓ |
| Rim ⌀ | 12.01 | 0.473 | ✓ |
| Belt ⌀ | n/a | ||
| Rim thickness | 1.37 | 0.054 | ✓ |
| Neck length | 7.24 | 0.285 | ≈ |
| Case length | 55.12 | 2.170 | ✓ |
| Overall length | 71.12 | 2.800 | ✓ |
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. .284 Winchester is highlighted below.
Factory loads
Being verified
Advertised FPS, energy, and BC are withheld until loads clear verification.
Suitable powders
14 reloading powders listed for .284 Winchester, 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.
Firearms chambered in .284 Winchester
7 models in the database chamber .284 Winchester. Browse all →
Lineage
Connected reference
History
Introduced by Winchester in 1963 for the Model 88 lever-action and Model 100 semi-automatic. The rebated rim — smaller than the case body — was an unusual engineering choice that allowed the large-capacity case to fit standard bolt faces. Despite good ballistics, commercial success was limited: the 7mm Remington Magnum debuted the same year and captured the market. Reloaders rediscovered the .284 Winchester in the 1990s–2000s precision community for its superior powder capacity compared to .308 Winchester in short-action rifles.
FAQs
- What twist rate does .284 Winchester use?
- .284 Winchester typically uses a 1:10 twist rate.
- What bullet diameter is .284 Winchester?
- .284 Winchester uses a 0.2839″ (7.21 mm) diameter bullet.
- Is .284 Winchester still in production?
- .284 Winchester is active; typical availability is limited.
- What is .284 Winchester used for?
- .284 Winchester is primarily used for hunting, target, competition.
- What are the best powders for .284 Winchester?
- Reloading powders commonly listed for .284 Winchester include N550, N555, Vihtavuori N140, N540, among 14 suitable options.
Sources & provenance
- Standard SAAMI — SAAMI cartridge & chamber drawing — .284 Winchester archived
- Standard C.I.P. — C.I.P. TDCC — Tables of Dimensions of Cartridges and Chambers
Data & sources. Specs compiled from the Lindcott Armory reference; availability counted from 17 live factory loads; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →