What twist rate does .38 ACP use?

.38 ACP typically uses a 1:16 twist rate.

What bullet diameter is .38 ACP?

.38 ACP uses a 0.356″ (9.042 mm) diameter bullet.

Is .38 ACP still in production?

.38 ACP is discontinued; typical availability is collector.

What is .38 ACP used for?

.38 ACP is primarily used for military, self defense.

Lindcott Armory

Pistol · SAAMI

.38 ACP

Also known as .38 Auto · .38 Automatic Colt Pistol · 9x23mmSR

Original John Browning semi-auto pistol cartridge for the Colt 1900 and Model 1902.

Caliber: 0.356″ · 9.042 mm
Introduced: 1900
Case: Semi-Rimmed
Primary use: Military, Self Defense
Status: Discontinued

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VelocityBeing verified

EnergyBeing verified

Typical grains130 gr

Identity

Introduced: 1900
Type: Pistol
Origin: United States
Inventor: John Browning
Manufacturer: Colt, Winchester
Standard: SAAMI
Status: Discontinued
Availability: Collector

Build

Case capacity: 16 gr H₂O
Twist (typical): 1:16
Primer: Small Pistol
Case type: Semi-Rimmed

Pressure & range

Max pressure: 26,500 psi
Eff. range: 50 yd
Max range: 100 yd
Recoil: 2.5–4 ft·lb
Subsonic: Capable

Ballistics

Published velocity/energy data isn't available for .38 ACP — an obsolete/collector cartridge.

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.

SAAMI · verified

Measure	mm	in	✓
Bullet ⌀	9.04	0.356	✓
Neck ⌀	9.75	0.384	✓
Shoulder ⌀	n/a
Shoulder angle	n/a
Base ⌀	9.75	0.384	✓
Rim ⌀	10.31	0.406	✓
Belt ⌀	n/a
Rim thickness	1.27	0.050	✓
Neck length	n/a
Case length	22.86	0.900	✓
Overall length	32.51	1.280	✓

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 ACP is highlighted below.

Factory loads

Verification

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.

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.

Firearms chambered in .38 ACP

11 models in the database chamber .38 ACP. Browse all →

Astra Astra 400 9mm Largo 6-inchAstra-Unceta Astra 400Webley & Scott Model 1905 Semi-Auto 9mmColt Model 1902 Military .38 ACPColt M1902 MilitaryWebley Fosbery Automatic Revolver 455Webley & Scott Webley-Fosbery Automatic Revolver .455 6-inchWebley & Scott Webley-Fosbery Automatic RevolverColt Model 1900 38 ACPColt M1900Webley Fosbery .455 Webley

Lineage

Family TreeOpen .38 ACP in the interactive cartridge family tree

Connected reference

FirearmsFirearms in .38 ACP

History

Developed by John Browning for Colt's first semi-automatic pistols (Model 1900, 1902, 1903). The cartridge was the basis of early US military semi-auto trials before the .45 ACP was adopted. In 1929, Colt introduced the .38 Super as a higher-pressure version of the .38 ACP for the M1911 platform. The .38 ACP is now a collector cartridge associated with early Colt semi-automatics.

FAQs

What twist rate does .38 ACP use?: .38 ACP typically uses a 1:16 twist rate.
What bullet diameter is .38 ACP?: .38 ACP uses a 0.356″ (9.042 mm) diameter bullet.
Is .38 ACP still in production?: .38 ACP is discontinued; typical availability is collector.
What is .38 ACP used for?: .38 ACP is primarily used for military, self defense.

Sources & provenance

Data & sources. Specs compiled from the Lindcott Armory reference; availability counted from 3 live factory loads; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →