What twist rate does .25 WSSM use?

.25 WSSM typically uses a 1:10 twist rate.

What bullet diameter is .25 WSSM?

.25 WSSM uses a 0.2575″ (6.54 mm) diameter bullet.

Is .25 WSSM still in production?

.25 WSSM is discontinued; typical availability is collector.

What is .25 WSSM used for?

.25 WSSM is primarily used for varmint, hunting.

What is .25 WSSM based on?

.25 WSSM is derived from the .300 WSM case.

What are the best powders for .25 WSSM?

Reloading powders commonly listed for .25 WSSM include Reloader 17.

Lindcott Armory

Rifle · SAAMI

.25 WSSM

Also known as .25 Winchester Super Short Magnum

The third and final WSSM — a .25-caliber super-short magnum.

Caliber: 0.2575″ · 6.54 mm
Introduced: 2004
Case: Rebated
Parent: .300 WSM
Primary use: Varmint, Hunting
Status: Discontinued

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VelocityBeing verified

EnergyBeing verified

Typical grains85 · 115 · 120 gr

Identity

Introduced: 2004
Type: Rifle
Origin: United States
Inventor: Winchester
Manufacturer: Winchester Ammunition
Standard: SAAMI
Status: Discontinued
Availability: Collector

Build

Case capacity: 54 gr H₂O
Twist (typical): 1:10
Primer: Large Rifle
Case type: Rebated

Pressure & range

Max pressure: 65,000 psi
Eff. range: 400 yd
Max range: 700 yd
Recoil: 10–15 ft·lb

Introduced by Winchester Ammunition

Ballistics

Published velocity/energy data isn't available for .25 WSSM — an obsolete/collector cartridge. Parent case: .300 WSM.

Performance

Best for Withheld until verified

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 ⌀	6.54	0.257	✓
Neck ⌀	7.60	0.299	✓
Shoulder ⌀	13.83	0.544	✓
Shoulder angle	30°	—	✓
Base ⌀	14.12	0.556	✓
Rim ⌀	13.59	0.535	✓
Belt ⌀	n/a
Rim thickness	1.37	0.054	✓
Neck length	7.63	0.300	≈
Case length	42.42	1.670	✓
Overall length	59.94	2.360	✓

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. .25 WSSM is highlighted below.

Factory loads

Verification

Being verified

Advertised FPS, energy, and BC are withheld until loads clear verification.

Suitable powders

1 reloading powder listed for .25 WSSM, fastest to slowest. Cross-reference in the finder →

Reloader 17

Reloading costestimate cost per round vs factory

Estimate your cost per round and how it compares to factory. Inputs are yours — nothing is stored.

Powder $/lb Charge (gr) Bullet $/ea Primer $/ea Brass reuses Brass $/ea

Cost estimate only — not load data. Charge weight is your input; follow published manuals for safe charges.

Lineage

Family TreeOpen .25 WSSM in the interactive cartridge family tree

Connected reference

Loads16 factory loads for .25 WSSM Reloading1 suitable powder — cross-reference FirearmsFirearms in .25 WSSM

History

Introduced in 2004, a year after the .223 and .243 WSSM. Factory ammunition was discontinued around 2018–2019. The .25 WSSM had the smallest following of the three WSSM cartridges due to limited .25-caliber bullet selection compared to .22 and .24 caliber options.

FAQs

What twist rate does .25 WSSM use?: .25 WSSM typically uses a 1:10 twist rate.
What bullet diameter is .25 WSSM?: .25 WSSM uses a 0.2575″ (6.54 mm) diameter bullet.
Is .25 WSSM still in production?: .25 WSSM is discontinued; typical availability is collector.
What is .25 WSSM used for?: .25 WSSM is primarily used for varmint, hunting.
What is .25 WSSM based on?: .25 WSSM is derived from the .300 WSM case.
What are the best powders for .25 WSSM?: Reloading powders commonly listed for .25 WSSM include Reloader 17.

Sources & provenance

Data & sources. Specs compiled from the Lindcott Armory reference; availability counted from 15 live factory loads; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →