The 450-400 Nitro Express, sometimes known as the 450/400 Nitro Express 3-inch, is a series of 405-411 caliber medium bore bottlenecked Nitro Express cartridges manufactured by W.J. Jeffery & Co in 1902 for use in single and double rifles. There were several varieties of each cartridge due to differences in cartridge lengths between manufacturers. The case lengths of the cartridges ranged from 314 to 238 inches (82.55 mm to 60.33 mm).
The 450-400 Nitro Express cartridges were all rimmed bottlenecked cartridges derived from several straight.450 Express cartridges. The.450 Nitro Express cartridges were necked down to take bullets with a diameter of.40 caliber (10.3 mm). Some of the original cartridges were shortened. There are differences in the dimensions of the cartridge rims. The rims of cordite (nitros) cartridges were thicker to help in the evacuation of trapped cases.
The 450-400 Nitro Express was designed as a low-pressure black-powder cartridge, and numerous gun companies produced weapons for it. As a result, there was some difference between each manufacturer's cartridges. While the bullet diameter was nominally specified as.405 inches, bores as large as.411 inches were known to exist. In a black-powder rifle, this may not have a major impact; but, in a Nitro Express, loading an undersized bullet in an enormous bore may create accuracy concerns, and firing an oversized bullet in an undersized bore may result in catastrophic failure of the firearm.
The 3-inch and 314-inch variants of the 450-400 Nitro Express was particularly popular in Africa and India. It was even regarded as Africa's greatest all-around hunting caliber.
