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The 8x64mm S (also unofficially known as the 8x64mm S Brenneke) (the S means it is intended for 8.2 mm (.323 in) groove diameter bullets) is a rimless bottlenecked centerfire cartridge developed as a military service round for the German Army who never issued it. As is customary in European cartridges the 8 denotes the 8 mm bullet caliber and the 64 denotes the 64 mm (2.52 in) case length. The 8x64mm is a hunting cartridge in central Europe and can due to its maximal overall length fairly easily be chambered in standard sized military Mauser 98 bolt action rifles. In such military M98 bolt actions the magazine boxes, however, have to be adapted by a competent gunsmith to function properly with the 8x64mm S cartridge, since the M98 internal magazine boxes feature an internal magazine length of . ==History== At the start of the 20th century the famous German gun and ammunition designer Wilhelm Brenneke (1865–1951) was experimenting with the engineering concept of lengthening and other dimensional changes regarding standard cartridge cases like the M/88 cartridge case, then used by the German military in their Mauser 98 rifles, to obtain extra muzzle velocity. In 1912 Brenneke designed the 8x64mm S cartridge. This cartridge is an example of a de novo rifle cartridge (the 8x64mm S and 6.5x64mm have no other cartridge as parent case) intended as a ballistic upgrade option for the Mauser Gewehr 98 rifles that were then standard issue in the German military. The exteriour cartridge case dimensions like overall length and slightly larger case head diameter compared to the German 8x57mm IS military cartridge coupled with a moderate increase in maximum pressure were chosen with easy conversion of Gewehr 98 rifles for the 8x64mm S in mind. Brenneke hoped that he could achieve a major success with this round designed in an age when military doctrine expected rifle shots at ranges up to 800 to 1000 m (875 to 1094 yards). The German military chose however to stick to their 8x57mm IS rifle cartridge avoiding rechambering their service rifles for a larger and heavier cartridge that due to its more favourable bore area to case volume ratio ballistically slightly outperforms the .30-06 Springfield cartridge introduced by the United States Army in 1906. Commercially the 8x64mm S was after an initial success phase in the period between the World Wars rather unsuccessful. Brenneke’s engineering concept to lengthen the 57 mm (2.244 in) long M/88 cartridge case to create new for those days very powerful cartridges was essentially sound and he persisted in the development of new cartridges like the commercially successful 7x64mm along this line. The 8x64mm S offered compared to the 8x57mm IS about 2 to 5% extra muzzle velocity. This results in a flatter trajectory and better performance at longer range. Beside the 8x64mm S rifle cartridge Brenneke also designed a rimmed version for break action rifles of the cartridge. The rimmed 8x65 mm RS variant of the cartridge was also rather commercially unsuccessful. 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「8×64mm S」の詳細全文を読む スポンサード リンク
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