.280 British

.280 British
Various .280 Ball Cartridges. Orange cased cartridge is made out of aluminium.
Type	Rifle
Place of origin	United Kingdom
Service history
Used by	British
Production history
Designer	British Army
Designed	1945
Specifications
Case type	rimless bottlenecked
Bullet diameter	.284 in (7.2 mm)
Neck diameter	.313 in (8.0 mm)
Shoulder diameter	.448 in (11.4 mm)
Base diameter	.470 in (11.9 mm)
Rim diameter	.473 in (12.0 mm)
Rim thickness	.049 in (1.2 mm)
Case length	1.71 in (43 mm)
Overall length	2.54 in (65 mm)
Ballistic performance
Bullet mass/type Velocity Energy 139 gr (9 g) Ball 2,545 ft/s (776 m/s) 1,980 ft·lbf (2,680 J) 140 gr (9 g) Ball 7 mm Mk 1Z 2,549 ft/s (777 m/s) 2,004 ft·lbf (2,717 J)
Source(s): Cartridge of the World

The .280 British was an experimental rimless bottlenecked intermediate rifle cartridge. It was later designated 7 mm MK1Z, and has also been known as 7 mm NATO, .280/30, .280 Enfield, .280 NATO, 7 mm FN Short, and 7×43mm. It was designed by the British Army in the late 1940s, with subsequent help from Fabrique Nationale in Belgium and the Canadian Army. The .280 British was tested in a variety of rifles and machine guns including the EM-2, Lee–Enfield, FN FAL, Bren, M1 Garand and Taden gun. Despite its success as an intermediate cartridge, the .280 British was not considered powerful enough by the U.S. Army and several variants of the .280 British were created in an attempt to appease the U.S. Army. However, the U.S. Army continued to reject these variants, ultimately adopting the 7.62×51mm NATO.

During World War II the standard British rifle and machine gun round was the venerable .303 British. Efforts to replace the .303 with a more modern round predated even World War I, but a series of events kept it in service in spite of its rimmed design causing a number of problems.

During the war the Allies encountered the new 7.92 "Kurz" cartridge on the battlefield and noted its effectiveness. The Kurz was an "intermediate power" round, less than a conventional rifle round like the .303, but more than pistol rounds like the 9mm Parabellum. This gave the Kurz rifle-like performance in close-range encounters, while still having a small enough recoil that it could be fired in fully automatic fire. This led British small arms designers to begin development of their own intermediate round.