.400 Jeffery Nitro Express

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.400 Jeffery Nitro Express
Illustration from the 1938-39 Westley Richards brochure
Type	Rifle
Place of origin	United Kingdom
Production history
Designer	W.J. Jeffery & Co
Designed	1902
Produced	1902–present
Specifications
Parent case	.450/400 Black Powder Express
Case type	Rimmed, bottleneck
Bullet diameter	.410 in (10.4 mm)
Neck diameter	.440 in (11.2 mm)
Shoulder diameter	.520 in (13.2 mm)
Base diameter	.548 in (13.9 mm)
Rim diameter	.625 in (15.9 mm)
Rim thickness	.065 in (1.7 mm)
Case length	3.00 in (76 mm)
Overall length	3.75 in (95 mm)
Case capacity	117.0 gr H2O (7.58 cm3)
Rifling twist	1-15 in (381 mm)
Primer type	Boxer
Maximum pressure	40,611 psi (280.00 MPa)
Ballistic performance
Bullet mass/type Velocity Energy 400 gr (26 g) 2,100 ft/s (640 m/s) 3,920 ft⋅lbf (5,310 J)
Test barrel length: 26 inches Source(s): Kynoch[1] & Barnes.[2]

The .400 Jeffery Nitro Express or .450/400 Nitro Express 3-inch is a medium bore, bottlenecked, Nitro Express cartridge designed by W.J. Jeffery & Co in 1902, intended for use in single shot and double rifles.