W.W. Greener deliberately designed this non-standard bore size (.730" rather than standard 12 gauge .729") so that standard commercial ammunition could not be used in the gun — and conversely the Greener cartridge could not be fired in a standard shotgun. Issued to British colonial police and prison services to prevent ammunition theft by prisoners. A uniquely pragmatic approach to arming armed guards in secure facilities.
Type: Shotgun
Introduced: 1921, United Kingdom
Parent case: None
Standardization: Proprietary
Bullet diameter: 0.73" (18.54 mm)
Case length: 2.756" (70 mm)
Max pressure: 25,000 PSI
Rim type: Rimless
Primer: 209 Shotshell
Typical twist rate: N/A (smoothbore)
Muzzle velocity: 1000–1150 fps
Muzzle energy: 800–1200 ft-lbs
Effective range: 100 yd
Primary use: military
Production status: Discontinued
Also known as: 12/14 Greener · Greener Police Gun · Greener Police Gauge
History: W.W. Greener's specialized shotgun/rifle cartridge for a unique police weapon he designed. The 12/14 gauge designation means the chamber accepts a 12 gauge shell but fires through a 14 gauge bore constriction, making the weapon incompatible with standard 12 gauge ammunition to prevent theft or misuse by criminals.