Pistol · SAAMI
.38-40 Winchester
A cowboy-era dual-use cartridge chambered in both Winchester rifles and Colt revolvers.
- Caliber
- 0.4004″ · 10.17 mm
- Introduced
- 1874
- Case
- Rimmed
- Parent
- .44-40 Winchester
- Primary use
- Cowboy Action, Self-Defense
- Status
- Active
- Introduced
- 1874
- Type
- Pistol
- Origin
- United States
- Inventor
- Winchester
- Manufacturer
- Winchester Repeating Arms
- Standard
- SAAMI
- Status
- Active
- Availability
- Common
- Case capacity
- 38.5 gr H₂O
- Twist (typical)
- 1:36
- Primer
- Large Pistol
- Case type
- Rimmed
- Max pressure
- 14,000 CUP, SAAMI crusher
- Eff. range
- 50 yd
- Max range
- 2050 yd
- Recoil
- 2–5.5 ft·lb
- Subsonic
- Capable
Introduced by Winchester Repeating Arms
Ballistics
Published velocity/energy data isn't available for .38-40 Winchester. Parent case: .44-40 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 ⌀ | 10.17 | 0.400 | ✓ |
| Neck ⌀ | 10.58 | 0.417 | ✓ |
| Shoulder ⌀ | 11.54 | 0.454 | ✓ |
| Shoulder angle | 6.8° | — | ✓ |
| Base ⌀ | 11.93 | 0.470 | ✓ |
| Rim ⌀ | 13.34 | 0.525 | ✓ |
| Belt ⌀ | n/a | ||
| Rim thickness | 1.65 | 0.065 | ✓ |
| Neck length | 5.87 | 0.231 | ≈ |
| Case length | 33.15 | 1.305 | ✓ |
| Overall length | 40.44 | 1.592 | ✓ |
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. .38-40 Winchester 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 .38-40 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 .38-40 Winchester
Lineage
Connected reference
History
The second in Winchester's rifle-revolver cartridge series (after .44-40). The '38' in the name refers to the case mouth diameter, not bullet size — it fires .401" bullets. Became the preferred cartridge of many lawmen and outlaws who wanted one ammunition type for both rifle and revolver.
FAQs
- What twist rate does .38-40 Winchester use?
- .38-40 Winchester typically uses a 1:36 twist rate.
- What bullet diameter is .38-40 Winchester?
- .38-40 Winchester uses a 0.4004″ (10.17 mm) diameter bullet.
- Is .38-40 Winchester still in production?
- .38-40 Winchester is active; typical availability is common.
- What is .38-40 Winchester used for?
- .38-40 Winchester is primarily used for cowboy action, self-defense.
- What is .38-40 Winchester based on?
- .38-40 Winchester is derived from the .44-40 Winchester case.
- What are the best powders for .38-40 Winchester?
- Reloading powders commonly listed for .38-40 Winchester include No. 2, Bull's-Eye, Universal, HP-38, among 5 suitable options.
Sources & provenance
- Standard SAAMI — ANSI/SAAMI Z299.4-2025 — Centerfire Rifle Velocity & Pressure Data · representative_gun, grain_ballistics archived
- Standard C.I.P. — C.I.P. TDCC — Tables of Dimensions of Cartridges and Chambers
- Standard SAAMI — SAAMI cartridge & chamber drawing — .38-40 Winchester archived
- Manufacturer Winchester Ammunition — Super-X Rifle — 44-40 Winchester 200 gr Power-Point (X4440) · grain_ballistics, representative_gun archived
- Manufacturer Black Hills — .38-40 — Authentic Cowboy Action · representative_gun, grain_ballistics archived
Data & sources. Specs compiled from the Lindcott Armory reference; availability counted from 32 live factory loads; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →
