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300 AAC Blackout, SAAMI short name 300 BLK, also known as 7.62×35mm is a rifle cartridge developed in the United States by Advanced Armament Corporation (AAC) for use in the M4 carbine. Its purpose is to achieve ballistics similar to the 7.62×39mm Soviet cartridge in an AR-15 platform while using standard AR-15 magazines at their normal capacity. ==History== While 5.56×45mm NATO has enjoyed widespread acceptance in military circles, the nature of the missions encountered by some special operations groups often demand a round that not only provides better performance than that available in the high-energy standard velocity rounds, but one that can offer subsonic performance greater than the current standard 9mm Luger round. In an effort to satisfy this need the 300 AAC Blackout was created by Advanced Armament Corporation in cooperation with Remington Defense, under the direction of AAC's Research and Development Director Robert Silvers and with the support of the company's founder, Kevin Brittingham. The project's goals were: * Create a reliable compact .30-cal solution for AR platform * Use existing inventory magazines while retaining their full capacity * Create the optimal platform for sound and flash suppressed fire * Create compatible supersonic ammo that matches 7.62×39mm ballistics * Provide the ability to penetrate barriers with high-mass projectiles * Provide all capabilities in a shorter, lightweight, durable, and low recoiling package Meeting these goals allowed the development team to negate many of the perceived drawbacks inherent to other large caliber cartridges when used in the M4 platform. Colt Firearms and other arms makers had previously chambered AR-pattern rifles and carbines in various .30 caliber rounds but several issues were encountered. In the case of the 7.62×39mm, its relatively severe case angle caused feeding issues unless specially modified AK-47 magazines were used, and even then results were less than outstanding. Modified bolts were also needed owing to its larger case head diameter. Rounds such as the 6.8 SPC and 6.5 Grendel had similar part-interchangeability issues but did allow for the use of the standard M4/M16 30-round magazine albeit with a reduced capacity. Wildcat cartridges such as the .300 Whisper series addressed these issues but their widespread use in single shot handguns along with the lack of an industry standard cartridge dimension meant that a great number of the popular loads on both the supersonic and subsonic end of the spectrum were less than ideal in the AR pattern weapons. Many of these rounds required an excessively long overall cartridge length that would prohibit feeding in a STANAG magazine while using powder charges that were not compatible with the pressure requirements of the M4 carbine. This was particularly noticeable when using subsonic ammunition in conjunction with a suppressor as short stroking and excessive fouling would occur similar to that which was seen in the earliest variants of the M16 in Vietnam. By keeping the M4/M16 platform in mind as the primary host during load development the designers were able to work up a host of cartridges that would satisfy not only the ballistic requirements set forth but also ensure mechanical reliability with the fewest changes to the weapon itself, with only a simple barrel change being necessary for a complete conversion. 300 AAC BLACKOUT was approved by SAAMI on January 17, 2011. On October 23, 2011, SSG Daniel Horner of the USAMU used 300 AAC Blackout to win his 4th USPSA Multi-Gun National Championship. 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「300 AAC Blackout (7.62×35mm)」の詳細全文を読む スポンサード リンク
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