Williamson Derringer
Moore's Patent Firearms Co. · Pistol · Discontinued · 1866
Also known as: Williamson's Patent Derringer
Overview
The Williamson Derringer is a single-shot .41 rimfire pocket pistol patented by David Williamson in 1866 and manufactured by Moore's Patent Firearms Co. and its successor the National Arms Company of Brooklyn, New York. Its defining feature is a removable steel auxiliary chamber with a central percussion nipple, allowing the owner to fire loose powder and ball with a percussion cap when metallic cartridges were unavailable, with no adjustment to the gun. The barrel slides forward for loading and is held in battery by an under-barrel latch.
Specifications
| Overall Length | 127 mm (5.00") |
| Barrel Length | 64 mm (2.52") |
| Action Type | Breech Loading |
| Firing Mechanism | Single Action |
| Trigger Type | Single Action |
| Muzzle Velocity | 130 m/s (427 fps) |
| Muzzle Energy | 71 J (52 ft·lbf) |
| Effective Range | 5 m (5 yd) |
| Barrel Rifling | Right Hand |
| Frame Material | Brass |
| Barrel Material | Steel |
| Stock Material | Walnut |
| Finish | Silver Plated |
Calibers
- .41 Short Rimfire · primary — also known as .41 Short, .41 Rimfire Short
Features
- Firing modes: Manual
- Feed systems: Manual Single Loading
- Safety mechanisms: Half Cock Barrel Latch Interlock
- Features: Sliding Barrel, Removable Percussion Chamber Insert, Dual Rimfire And Percussion, Pocket Pistol
Production
Estimated total produced: 10,000 · Production years: 1866-1870
Serial ranges suggest up to ~20,000, though actual production may have been roughly half that; uncertain.
Origin
Country of origin: United States
Designer: David Williamson
Discontinued: 1870
Notes
Dual rimfire and percussion capability via the removable chamber insert; half-cock safety locks the barrel latch.
Background
The percussion-insert feature was a clever hedge for a period when metallic cartridges could be hard to find on the frontier, letting the Williamson serve as both a cartridge and a cap-and-ball pistol.