.280 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. 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 designers had accomplished their goals, and proceeded to introduce the cartridge to their NATO allies. Counterparts in Belgium and Canada proved very interested, and the Belgian company FN would introduce their own gun designs based on the .280 as well as produce the rounds in quantity. However, the Americans refused to adopt a calibre under .30 inch, or with ballistics inferior to the then-standard .30-06 Springfield round. The British then attempted to appease the Americans though a series of changes to the round. The first was a small change to the rim diameter of the .280 to the size of the .30-06 Springfield to produce the .280/30 cartridge, which was produced in large numbers and is the basis of the dimensions listed to the right. The .280/30 cartridge weighed , making it a rather heavy cartridge by intermediate standards. When the .280/30 was rejected by the Americans as being too weak with too great a drop in trajectory beyond , the British and Belgians made larger 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 concept. 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