Pistol · Military · Not SAAMI standardized · Not standardizedObsolete
.30 Pedersen
Unique WWI cartridge developed for the secret Pedersen Device that converted the M1903 Springfield into a semi-automatic rifle; one of the most historically significant forgotten American cartridges..
- Caliber
- 0.3102″ · 7.88 mm
- Introduced
- 1918
- Case
- Semi-Rimless
- Primary use
- Self-Defense, Target
- Status
- Discontinued
- Obsolete
- Obsolete
- Introduced
- 1918
- Type
- Pistol
- Origin
- United States
- Inventor
- John Pedersen
- Manufacturer
- United States state arsenals
- Standard
- Military · Not SAAMI standardized · Not standardized
- SAAMI
- Not SAAMI standardized
- Obsolete
- Obsolete
- Status
- Discontinued
- Availability
- Rare
- Case capacity
- 11.2 gr H₂O
- Twist (typical)
- 1:16
- Primer
- Boxer Small Pistol
- Case type
- Semi-Rimless
- Max pressure
- 14,500 CUP, SAAMI crusher
- Eff. range
- 100 yd
- Max range
- 2150 yd
- Recoil
- 4.3–5.2 ft·lb
- Subsonic
- Capable
Ballistics
Velocity only, no drag model: no published ballistic coefficient is on file for .30 Pedersen, so this is the shape gravity alone gives the advertised velocity. Drag would steepen it. The tool below solves real loads through their published G1 or G7 model.
Open in Ballistic Compare- Parent case
- —
Representative trajectory — modeled from a single velocity input (no published BC for this cartridge yet).
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 · approximate| Measure | mm | in | ✓ |
|---|---|---|---|
| Bullet ⌀ | 7.88 | 0.310 | ~ |
| Neck ⌀ | 8.55 | 0.337 | · |
| Shoulder ⌀ | n/a | ||
| Shoulder angle | n/a | ||
| Base ⌀ | 8.55 | 0.337 | · |
| Rim ⌀ | 8.55 | 0.337 | · |
| Belt ⌀ | n/a | ||
| Rim thickness | 1.05 | 0.041 | · |
| Neck length | n/a | ||
| Case length | 19.70 | 0.776 | ~ |
| Overall length | 27.58 | 1.086 | |
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. .30 Pedersen is highlighted below.
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 .30 Pedersen
Lineage
Connected reference
History
Developed in 1918 by John Pedersen for his secret 'Pedersen Device,' which converted the M1903 Springfield bolt-action rifle to fire semi-automatically using a blow-back mechanism. The .30 Pedersen cartridge was produced in quantity in preparation for the 1919 offensive that never came due to the Armistice. General Pershing called the Pedersen Device the greatest military secret of WWI. All devices and most ammunition were destroyed afterward.
FAQs
- What twist rate does .30 Pedersen use?
- .30 Pedersen typically uses a 1:16 twist rate.
- What bullet diameter is .30 Pedersen?
- .30 Pedersen uses a 0.3102″ (7.88 mm) diameter bullet.
- Is .30 Pedersen still in production?
- .30 Pedersen is discontinued; typical availability is rare.
- What is .30 Pedersen used for?
- .30 Pedersen is primarily used for self-defense, target.
Sources & provenance
- Reference Thomas/Ray Riling Arms Books (Hackley, Woodin & Scranton) — History of Modern U.S. Military Small Arms Ammunition, Vol. I · bullet ⌀, velocity, grain weights
- Secondary Cartridge Collector (cartridgecollector.net) — 30 Pedersen Device · year archived
- Secondary American Rifleman (NRA) — The Pedersen Device: A Secret Weapon of WWI · grain weights, velocity archived
Data & sources. Specs compiled from the Lindcott Armory reference; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →
