The .280 British, (also known as 7 mm NATO, .280/30, .280 Enfield, .280 NATO, 7 mm FN Short, 7x43 mm) later designated "7 mm MK1Z", was an experimental intermediate rifle cartridge designed by the British Army in the late 1940s (later with help from Fabrique Nationale in Belgium) and the Canadian Army). The .280 British was tested in a variety of rifles and machineguns including the EM-2, Lee-Enfield, FN FAL, M1 Garand and Taden gun. Despite its success as an intermediate cartridge, the .280 British was not considered powerful enough by the US Army and several variants of the .280 British were created in an attempt to appease the US Army. The US Army would continue to reject these variants, ultimately adopting the 7.62×51 NATO which forced NATO to do the same.
After the end of World War, the British, having encountered new assault rifle cartridges such as the 7.92 "Kurz" on the battlefield, set about replacing their venerable .303. Their goal was to create a cartridge that would replace all small arms in .303 including the Bren, the No.4 rifle and the crew served Vickers with a cartridge suitable for a "light rifle". Thus the cartridge had to demonstrate ballistic performance equal to that of a full powered rifle round and yet exhibit as little recoil and blast as possible. After extensive tests by the "Ideal Cartridge Panel" in 1945, the British decided upon two 7 mm cartridges – the .270 and the .276. In order to focus their efforts, the British ceased research on the .270 and concentrated their efforts on the .276. The .276 was later renamed the .280 even though no dimensions were changed. To add additional confusion the .280 actually has a bullet with a diameter of .284 inches. (The .276 is the measurement of the distance between the rifling lands in the barrel.) Recoil was calculated to be a little under half of the .303. Long range performance actually surpassed that of the .303, and shooters reported that it was much more comfortable to fire with the reduced recoil and reduced blast. It seemed that the British had accomplished their goals. They were soon eager to demonstrate the cartridge to the NATO allies. The AK-47 is the worlds most common assault rifle. ... 7. ... .303 cartridge The . ... The Bren (from Brno (the Czechoslovakian town of design) and Enfield, the location of the British Royal Small Arms Factory), usually called the Bren Gun, was a series of squad automatic weapon/light machine guns adopted by Britain in the 1930s and used in various roles into the 1980s. ... The Vickers machine gun or Vickers gun is a name primarily used to refer to the water-cooled . ... Year 1945 (MCMXLV) was a common year starting on Monday (the link is to a full 1945 calendar). ...
However it was not meant to be. Despite interest from the Belgians (FN would later produced the .280 in quantity and help improve it) and the Canadians, the Americans were not at all interested, claiming they would not adopt a caliber under .30. The British attempted to appease the American biases, first with small changes such as changing the rim diameter of the .280 to the size of the .30-06 (resulting in the .280/30 cartridge which was produced in large numbers) and when the .280/30 was outright rejected by the Americans as being too weak with too great a drop in trajectory, the British and Belgians made large changes to the cartridges. These resulted in several different variations, one was just a .280/30 with the bullet seated less deeply so more powder would be put in the case, another was a T65 cartridge case (the T65 would later be the 7.62x51 NATO) necked down to 7 mm. In the end the different cartridges the British and the Belgians came up with fired 140 grain bullets at around 2700 to 2800 FPS, but at a much greater blast and recoil than the .280/30, which defeated the intentions of the initial .280 venture. Unsatisfied with the US Army dragging its feet on the issue, in 1951 the British adopted the EM-2 and the .280/30 as their primary rifle and ammunition with the .280/30 being redesignated as the "7 mm MK1Z". However, this effort was all in vain, and the Americans unilaterally adopted the T65, later to be designated the 7.62x51 NATO. 1951 (MCMLI) was a common year starting on Monday; see its calendar. ...
The 7 mm, EM-2 and Taden gun projects were abandoned soon after by Winston Churchill, who desired to have commonality between the NATO countries. Small amounts of .280 would be produced in the 1960s for various small arms trials. With the American recognition that the 7.62x51 NATO was too powerful a cartridge (and the subsequent change to 5.56x45 NATO) , the .280 concept proved to have been a sound one and ahead of its time.
Performance
The following comparisons are excerpts from a manual published by the "Small Arms Group Armament Design Establishment" from the Ministry of Supply[1]:
.280 .303 .30/06
Bullet weight in grains 139 174 166
Muzzle velocity in ft/s 2500 2456 2770
Timber penetration at 2,000 yards 2.9" 2.4" 1.6"
Timber penetration at 100 yards 45" 42" 47"
Range for penetration of airborne type steel helmet 1000 yards 900 yards 1600 yards
Vertex height in feet for 600 yard range 3.3 3.1 3.0
Recoil energy per round (smaller is less recoil) 7.4 ft·lbf with EM-2 11.0 ft·lbf with No.4 Rifle 14.4 ft·lbf with the Garand
Variants
* .270: Designed at the same time as the .280. It has a slightly smaller bullet diameter of .279 inches but a lighter bullet (93 to 100 grains) with a greater muzzle velocity (2750–2800 fps), longer case (1.8 inches) and shorter OAL (2.45 inches). Research was abandoned in 1948.
* 7 mm "Optimum": The original .280 round with the bullet seated less deeply, giving an OAL of 2.6 inches.
* 7 mm "High Velocity": Longer case (1.95 inches), with an OAL of 2.79 inches. Similar 140 grain bullet fired at 2750 FPS.
* 7 mm "Compromise" (aka T65/7 mm): Necked down T65 (7.62x51 NATO) to 7 mm. Case length 2 inches, OAL 2.8 inches, similar 140 grain bullet fired at 2800 ft/s.
* 7 mm "Second Optimum" (7x49 mm) : Designed by FN. Also known as the 7 mm "Medium" and the 7 mm "Liviano". FN would later sell FAL rifles chambered in this caliber along with a sizeable amount of ammuition to Venezuela. Longer case (1.935 inches) with an OAL of 2.78 inches. 140 grain bullet fired at 2755 ft/s.
* 6.25 mm (6.25x43 mm): A British experimental cartridge designed during the early 1970s, using the .280/30 as a parent case, which was necked down to fit a smaller bullet.
References
1. ^ Reprinted by Dugelby, Thomas B.. EM-2 Concept & Design; a rifle ahead of its time, Collector Grade Publications, 1980, p. 247
* Dugelby, Thomas B. (1980). EM2: Concept and Design. Toronto: Collector Grade Publications.
* Labbett, P; P.J.F Mead. Technical Ammunition Guide: British 7mm Ammunition.
* Stevens, R. Blake (1993). The FAL rifle. Toronto: Collector Grade Publications. ISBN 0-88935-168-6.
* Popenker, Maxim; Anthony G. Willams (2005). Assault Rifle. Ramsbury: Crownwood Press Ltd. ISBN 1-86126-700-2.
