Rifle · SAAMI
.243 WSSM
Super-short .243-caliber magnum delivering .243 Winchester velocities in a stubby case.
- Caliber
- 0.243″ · 6.172 mm
- Introduced
- 2003
- Case
- Rebated
- Parent
- .300 WSM
- Primary use
- Varmint, Hunting
- Status
- Discontinued
- Introduced
- 2003
- Type
- Rifle
- Origin
- United States
- Inventor
- Winchester
- Manufacturer
- Winchester Ammunition
- Standard
- SAAMI
- Status
- Discontinued
- Availability
- Collector
- Case capacity
- 53 gr H₂O
- Twist (typical)
- 1:10
- Primer
- Large Rifle
- Case type
- Rebated
- Max pressure
- 65,000 psi
- Eff. range
- 400 yd
- Max range
- 700 yd
- Recoil
- 8–12 ft·lb
Introduced by Winchester Ammunition
Ballistics
Published velocity/energy data isn't available for .243 WSSM — an obsolete/collector cartridge. Parent case: .300 WSM.
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 · verified| Measure | mm | in | ✓ |
|---|---|---|---|
| Bullet ⌀ | 6.17 | 0.243 | ✓ |
| Neck ⌀ | 7.39 | 0.291 | ✓ |
| Shoulder ⌀ | 13.82 | 0.544 | ✓ |
| Shoulder angle | 28° | — | ✓ |
| Base ⌀ | 14.10 | 0.555 | ✓ |
| Rim ⌀ | 13.59 | 0.535 | ✓ |
| Belt ⌀ | n/a | ||
| Rim thickness | 1.37 | 0.054 | ✓ |
| Neck length | 7.16 | 0.282 | ≈ |
| Case length | 42.42 | 1.670 | ✓ |
| Overall length | 59.99 | 2.362 | ~ |
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. .243 WSSM is highlighted below.
Factory loads
Being verified
Advertised FPS, energy, and BC are withheld until loads clear verification.
Suitable powders
5 reloading powders listed for .243 WSSM, 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
Part of Winchester's 2003 WSSM family. The .243 WSSM achieved the highest velocities of the three WSSM cartridges and was arguably the most practical for deer hunting. Factory ammunition was discontinued around 2018–2019 after Browning discontinued the A-Bolt WSSM platform.
FAQs
- What twist rate does .243 WSSM use?
- .243 WSSM typically uses a 1:10 twist rate.
- What bullet diameter is .243 WSSM?
- .243 WSSM uses a 0.243″ (6.172 mm) diameter bullet.
- Is .243 WSSM still in production?
- .243 WSSM is discontinued; typical availability is collector.
- What is .243 WSSM used for?
- .243 WSSM is primarily used for varmint, hunting.
- What is .243 WSSM based on?
- .243 WSSM is derived from the .300 WSM case.
- What are the best powders for .243 WSSM?
- Reloading powders commonly listed for .243 WSSM include N550, Vihtavuori N140, N540, Reloader 17, among 5 suitable options.
Sources & provenance
- Standard SAAMI — ANSI/SAAMI Z299 — Cartridge & Chamber Drawings archived
- Standard SAAMI (Sporting Arms and Ammunition Manufacturers' Institute) — ANSI/SAAMI Z299.4 – 2015 (Centerfire Rifle) — Velocity & Pressure / Cartridge & Chamber Drawings · grain_ballistics, representative_gun archived
- Manufacturer Winchester Ammunition — Winchester product sheet — SBST243SS, 243 WSSM 55 gr. Supreme Ballistic Silvertip (archived winchester.com) · grain_ballistics, representative_gun
- Manufacturer Winchester Ammunition — Winchester product sheet — SBST243SSA, 243 WSSM 95 gr. Supreme Ballistic Silvertip (archived winchester.com) · grain_ballistics, representative_gun
- Manufacturer Winchester Ammunition — Power-Point rifle ammunition — 358 Winchester, symbol X3582 · grain_ballistics, representative_gun
Data & sources. Specs compiled from the Lindcott Armory reference; availability counted from 22 live factory loads; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →