Both the .450/400 2-inch NE and .450/400 3-inch NE were created by loading the
.450/400 Black Powder Express cartridges of both case lengths with smokeless
cordite.
.450/400 2-inch Nitro Express The .450/400 2 inch Nitro Express was loaded with a 400 gr. RN bullet with 42 or 43 grains of cordite, and meant for use in newer rifles chambered for it, as this loading generates greater pressure than the Black Powder Express versions of the cartridge.
.450/400 3-inch Nitro Express This cartridge is better known as the
.400 Jeffery Nitro Express.
.450/400 3-inch Nitro Express The .450/400 3-inch NE conversion was not initially entirely successful, under the increased pressures of the cordite loading the long neck could stick in the chamber causing the rim to pull off at extraction, a problem not encountered under the milder black powder loadings. To counter this, the rim was increased in thickness to .042-inches.
W. J. Jeffery & Co. further improved the cartridge by reducing the length of the case to 3-inches and moving the neck further forward, creating the .450/400 3-inch NE. Additionally, the caliber had to be standardised, slight variations existed in both the rifles and the low-pressure black powder cartridges produced by different manufacturers, the bullet diameter is nominally given as .405 inches, bore as large as .411 existed, not a significant problem in black-powder rifles. In Nitro Express loadings, an undersized bullet in an oversized bore may experience accuracy issues while an oversized bullet fired in an undersized bore may cause a catastrophic failure in the firearm. The .450/400 3-inch Nitro Express fires a 400 gr. jacketed bullet ahead of a charge of 56 - 60 gr. of cordite at a velocity of . This cartridge is considered unsafe to use for older rifles chambered for the black powder version of this cartridge due to higher pressures generated by this loading. .450/400 3-inch Nitro Express rifles are heavier and were considered as the minimum cartridge necessary when hunting dangerous game. ==Use==