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.333 Jeffery
Type Rifle
Place of originUnited Kingdom
Service history
In serviceUK
Used byBritish Army
WarsWorld War I
Production history
DesignerW.J. Jeffery
ManufacturerW.J. Jeffery & Co.
Variants.333 Jeffery Flanged
Case typeRimless, bottlenecked
Bullet diameter.333 in (Bad rounding hereScript error mm)
Neck diameter.365 in (Bad rounding hereScript error mm)
Shoulder diameter.500 in (Bad rounding hereScript error mm)
Base diameter.545 in (Bad rounding hereScript error mm)
Rim diameter.543 in (Bad rounding hereScript error mm)
Rim thickness.050 in (Bad rounding hereScript error mm)
Case length2.475 in (Bad rounding hereScript error mm)
Overall length3.500 in (Bad rounding hereScript error mm)
Case capacity84.0 gr H2O (Bad rounding hereScript error cm3)
Maximum pressure46,000 psi (Bad rounding hereScript error MPa)
Ballistic performance
Bullet weight/type Velocity Energy
250 gr (Script error g) SP 2,500 ft/s (Bad rounding hereScript error m/s) 3,480 ft·lbf (Bad rounding hereScript error J)
300 gr (Script error g) SP 2,200 ft/s (Bad rounding hereScript error m/s) 3,230 ft·lbf (Bad rounding hereScript error J)

The .333 Jeffery also known as the .333 Jeffery Rimless Nitro Express or as the .333 Rimless Nitro Express is a rimless bottlenecked cartridge. It was developed by the W.J. Jeffery & Co in 1908 as a counterpart to the .333 Jeffery Flanged and was intended for use in magazine rifles.[1]

General informationEdit

The .333 Jeffery was designed for hunting medium game in Africa and India where it gained a following. While the cartridge is not intended for dangerous game, the cartridge was successfully used against these game species due to the excellent sectional density of the 300 gr (Bad rounding hereScript error g) bullet.[1] The penetrative capability of this bullet was a reason for its use as a counter sniper rifle cartridge between 1914 and 1918 as it could penetrate the German sniper shields before reaching the snipers.[2]

The .333 Jeffery was originally loaded with cordite. It is loaded to a slightly higher pressure and performance level than its rimmed counterpart. The .333 OKH cartridge and the .318 Westley Richards cartridges provide similar performance levels as the .333 Jeffery.

Kynoch offers the loaded ammunition for the cartridge. They offer a 250 gr (Bad rounding hereScript error g) bullet at 2,400 ft/s (Bad rounding hereScript error m/s) and a 300 gr (Bad rounding hereScript error g) bullet at 2,150 ft/s (Bad rounding hereScript error m/s).[3] Brass of new manufacture can be obtained from Bertram Brass of Australia and Kynoch.


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