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The .260 Remington (also known as 6.5-08 A-Square) cartridge was introduced by Remington in 1997. Many wildcat cartridges based on the .308 Winchester case had existed for years before Remington standardized this round. Although loaded to higher pressures, the ballistics of this cartridge are basically similar to the 6.5×55mm when bullet weights do not exceed 140 grains. When loaded with heavier bullets, the 6.5×55mm is capable of greater velocity.〔2002, ''Lyman's Reloading Handbook, 48th Edition''〕 Due to its shorter overall length the .260 Remington can be chambered in a shorter length bolt action than the 6.5mm Swedish. Because 6.5 mm (.264") bullets have relatively high ballistic coefficients, the .260 Remington has seen success in rifle competition. It is capable of duplicating the trajectory of the .300 Winchester Magnum while generating significantly lower recoil.〔(【引用サイトリンク】first= )〕 Also, converting a rifle chambered for the .308 Winchester (or any of its offspring, such as the .243 Winchester, 7mm-08 Remington or .338 Federal) to .260 Remington generally requires little more than a simple barrel change. ==Origin & history== Remington has had a track record of adopting successful wildcat cartridges into the Remington fold by offering rifles and ammunition and at times attaching their name to the cartridge.〔(【引用サイトリンク】first=Simpson )〕 Like many cartridges such as the .22–250 Remington, .25-06 Remington and the 7 mm-08 Remington, the .260 Remington started its life as a wildcat cartridge called the 6.5-08 and was eventually released as a commercial cartridge by Remington. However, it was not Remington who first attempted to standardize the cartridge. LTC Arthur Alphin and his company A-Square LLC submitted the first proposal and drawings to SAAMI for the standardization of the cartridge. Remington was to file similar papers with SAAMI to do the same a few months later. When the dust settled it was found that the 6.5-08 would be called the .260 Remington instead of 6.5–08 A-Square. The 6.5 -08 cartridge was created simply by necking down the .308 Winchester.〔Sundra, Jon R. "Guns & Ammunition", in ''Safari: The Journal of Big Game Hunters'', Safari Club International, Nov-Dec 2009, p.142.〕 Handloaders and wildcatters can easily form .260 cases by necking down the 7mm-08 Remington or necking up the .243 Winchester (both based on the same .308 case).〔Sundra, p.142.〕 Since the parent cartridges were readily available for low cost, the 6.5 -08 was often an economical alternative to cartridges such as the 6.5×55mm Swedish Mauser. What the 6.5-08 provided over the .243 Winchester, .308 Winchester and to a lesser degree the 7mm-08 Remington was bullets with excellent ballistic coefficients and sectional densities relative to their weights. Since the 6.5-08 was a wildcat cartridge, there were variations between cartridge chambers depending on the reamer used to cut the chamber. Furthermore, depending on whether one chose to form the case from .243 Winchester or .308 Winchester influenced the neck thickness and therefore the dimensions of the cartridge. A cartridge formed for a specific rifle may or may not successfully chamber or worse may reach dangerous pressures in another. Standardizing the cartridge addressed the issues owners experienced when it was a wildcat. .264 (6.5 mm) caliber has historically been unsuccessful in North America but has been one of the mainstays in Europe especially in the Scandinavian countries. The 6.5×54mm Mannlicher–Schönauer, 6.5×55 Swedish Mauser, 6.5×57 Mauser, and 6.5-284 Norma have loyal followings in Europe. Starting with the .264 Winchester Magnum and later the 6.5mm Remington Magnum, North American cartridges in this caliber have been largely failures. The .260 Remington appeared to be following this North American trend, with Remington only producing the Model Seven Synthetic in the .260 Remington for 2011 as it has discontinued such rifles as the Model 700 CDL and the Model Seven (including the youth model) in .260. However, Remington continues to manufacture several types .260 Remington loads. The use of the .260 Remington by SGT Sherri Gallagher to win the 2010 NRA High Power National Championship has sparked a resurgence in the round, and Lapua announced at the 2011 SHOT show that it would be manufacturing .260 Remington brass. 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「.260 Remington」の詳細全文を読む スポンサード リンク
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