.400/350 Nitro Express

The .400/350 Nitro Express is a centerfire, rifle cartridge developed by John Rigby & Company.

Development
Introduced in 1899, the .400/350 Nitro Express is a rimmed cartridge originally designed for use in single-shot and double rifles. In 1899 Rigby approached the engineers at Mauser to make a special Gewehr 98 bolt action to handle this cartridge, its introduction in 1900 was the birth of the magnum length bolt action, paving the way for such cartridges as the .375 H&H and .416 Rigby.

The .400/350 Nitro Express fires a .358" diameter 310 grain projectile at either 2000 fps or 2150 fps, depending on the source. The later .350 Rigby No 2 uses the same cartridge case but fires a lighter projectile at higher velocities.