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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. ==History== After the Second World War the British, having encountered the new 7.92 "Kurz" cartridge on the battlefield and noted its effectiveness, began a programme to replace the venerable .303 British cartridge which had been marked for replacement but had survived as a consequence of wartime pressures on British small arms development. The goal of the British designers was to create a cartridge that would replace all small arms in .303 calibre including the Bren, the No.4 Rifle and the Vickers medium machine gun 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, so that it was controllable during rapid or automatic fire. A shorter cartridge producing lower recoil also enabled the weapon to be shorter and lighter, and hence easier to use. After extensive tests by the "Ideal Cartridge Panel" in 1945, the British decided upon two 7 mm cartridges – the .270 and the .276. Both designations reflected the measurement of the distance between the rifling lands in the cartridges' respective barrels; the .276 bullet's actual diameter was . 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 British even though no dimensions were changed. Recoil of the .280 British cartridge was calculated to be a little under half of the .303 British. Long range performance actually surpassed that of the .303 British, and shooters reported that it was much more comfortable to fire with the reduced recoil and reduced blast. It seemed that the British designers had accomplished their goals, and proceeded to introduce the cartridge to their NATO allies. Despite interest from the Belgians (FN would later produce the .280 British in quantity and help improve it) and the Canadians, the Americans were not at all interested, claiming they would not adopt a calibre under .30 inch, or with ballistics inferior to the then-standard .30-06 Springfield round. The British attempted to appease the Americans, first with small changes such as changing the rim diameter of the .280 British to the size of the .30-06 Springfield (resulting in the .280/30 cartridge which was produced in large numbers and is the basis of the dimensions listed to the right). Later, when the .280/30 was rejected by the Americans as being too weak with too great a drop in trajectory, the British and Belgians made large changes to the cartridge design. These resulted in several different variations; one was just a .280/30 with the bullet seated less deeply so more powder could be put in the case, another was a T65 cartridge case necked down to 7 mm. The different cartridges that the British and Belgians eventually came up with fired bullets at around , but with a much greater blast and recoil than the .280/30, which defeated the design parameters of the initial .280 British venture. Unsatisfied with the U.S. Army's response on the issue, the British adopted the EM-2 and the .280/30 as their primary rifle and ammunition in 1951 with the .280/30 being re-designated as the "7 mm MK1Z". This effort was to be all in vain, as the Americans adopted the T65 (later to be designated the 7.62×51mm NATO). During this period, it was discovered that Colonel Renée Studler, head of the US Small Arms Bureau of Ordnance had been diametrically opposed to a bullpup design and .280 cartridge because it was 'foreign', going so far as hiding reports concluding that the .280 and the EM2 were superior. Britain, Canada and the United States founder members of NATO, had all signed an agreement that member states would develop and deploy with, common small arms and cartridges developed through competitive trials in co-operation together. Britain and Canada had been open about their developments, however, the Americans although they were trialling the British designs - stated they had not commissioned any development work of their own. Subsequently, the British discovered that Colonel Studler was operating a highly confidential rifle programme run by Earle Harvey called the 'T25' at Springfield Armoury while at the same time at Frankford Arsenal he was running ''another'' top secret parallel programme, code-named 'T65', based on the development of a .30 cartridge. Between 1947 and 1952 the British and Canadians made clear to the United States they were aware of their secret work, stating that it was against the open, collaborative nature of the agreement, making their disapproval clear. Eventually, the British and Canadians realised the Americans would only support their own designs. Matters took a turn for the worse when Renee Studler went on record, stating that, any non-American design was a "a waste of time" and refused point blank to accept any 'foreign' design. A change of government meant that the 7 mm, EM-2 and Taden gun projects were abandoned soon afterwards by Winston Churchill, who returned as the prime minister and desired commonality between the NATO countries. Small amounts of .280 British ammunition were later produced during the 1960s for various small arms trials. At the same time, the British and Canadians, who were very impressed with the cartridge originally planned to have their FN FAL rifles chambered in .280. However, eventually they agreed in a quid pro quo to accept the US-derived .30 (by now the 7.62) while the Americans accepted the FN FAL. The .280 British concept would later prove to have been far ahead of its time, as the U.S. itself adopted an intermediate cartridge — 5.56×45mm NATO — by the end of the following decade. Soon after America's large-scale involvement in Vietnam commenced in 1965 the 5.56×45mm NATO ArmaLite AR-15 rifle, later standardised as the M16, was purchased in ever increasing numbers and by the late 1960s had displaced the 7.62×51mm NATO M14 rifle in combat units. After insisting on a .30 calibre round with full-power ballistics almost identical to those of the existing .30-06 Springfield, the U.S. then adopted the 5.56×45mm NATO intermediate cartridge, which demonstrated the emergence and dominance of intermediate cartridges on the battlefield (the other notable one being the 7.62×39mm AK-47 round). The adoption of the 7.62×51mm NATO round and the adaptation of the intermediate cartridge CETME (later developed into the Heckler & Koch G3) and FN FAL designs to fire it, produced rifles that were relatively longer and heavier and had greater recoil. The result was weapons that performed well as longer-range semi-automatic rifles, but were more cumbersome and only marginally controllable in automatic fire. These guns also had a higher training burden and were not well suited to soldiers of smaller stature, again due to the recoil. Coincidentally, in 2002 the Americans developed a military calibre intended for the M4 version of the M16 family called the 6.8mm Remington SPC — with similar ballistic properties to the .280 British cartridge — which was intended to provide better ballistics than the 5.56×45mm NATO. In the late 1960s, a version of the .280 British was created using a 6.25 mm bullet in a necked-down .280 British case. It was designed in response to experiments in the U.K. trying to find an ideal military small-arms round. Large caliber bullets were calculated to need more energy to penetrate various levels of body armor to inflict disabling wounds on soldiers. Out of several "optimum solutions" ranging from 4.5 mm to 7 mm, the 6.25 mm was the preferred solution. The bullet had a muzzle velocity of and of muzzle energy. While the 7.62×51mm NATO required of force on impact to penetrate helmets and heavy body armor, the 6.25 mm required only of impact force to deliver the same penetration effects out to 600 m. It remained effective for a longer distance and produced recoil closer to that of the 5.56×45mm NATO.〔(ASSAULT RIFLES AND THEIR AMMUNITION: HISTORY AND PROSPECTS by Anthony G Williams )〕 However, it was not designed for very long range and its bullet was relatively light.〔(The Case for a General-Purpose Rifle and Machine Gun Cartridge (GPC) by Anthony G Williams )〕 Testing of the 6.25×43mm was conducted from 1969 to 1971, when development ceased in favor of the smaller 4.85×49mm.〔(6.25x43mm Experimental ) - Militarycartridges.nl〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「.280 British」の詳細全文を読む スポンサード リンク
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