Yiyuan Rong Cave Group and Knight's Armament Company PDW

The Yiyuan Rong Cave Group (Chinese: 沂源溶洞群; pinyin: Yíyuán Róng Dòng Qún) is a cluster of Ordovician limestone caves in the area under the administration of the city of Zibo, Shandong Province, China. Rong Cave proper (Chinese: 沂源溶洞; pinyin: Yíyuán Róng Dòng, 36°16′06″N 118°04′14″E / 36.268428°N 118.070669°E / 36.268428; 118.070669Coordinates: 36°16′06″N 118°04′14″E / 36.268428°N 118.070669°E / 36.268428; 118.070669) is the namesake of the cave group. It is located about 13 kilometres (8.1 mi) to the north of the town of Tumen (Chinese: 土门镇; pinyin: Tŭmén Zhèn). The cave group contains more than 40 caves in total and is the largest cluster of limestone caves in China north of the Yangtze River. It covers an area of approximately 10 square kilometers. Other major caves in the group are Thousand-Men Cave (Chinese: 千人洞; pinyin: Qiānrén Dòng), Resting Cave (Chinese: 养神洞; pinyin: Yǎngshén Dòng), Stone-Dragon Cave (Chinese: 石龙洞; pinyin: Shílóng Dòng), Xuanyun Cave (Chinese: 玄云洞; pinyin: Xuányún Dòng), Nine-Skies Cave (Chinese: 九天洞; pinyin: Jiŭtiān Dòng), Coral Cave (Chinese: 珊瑚洞; pinyin: Shānhú Dòng), Lingzhi Cave (Chinese: 灵芝洞; pinyin: Língzhī Dòng, after the Lingzhi mushroom), Shenxian Cave (Chinese: 神仙洞; pinyin: Shénxiān Dòng), and Xiaya Cave (Chinese: 下崖洞; pinyin: Xiàyá Dòng, 36°14′36″N 118°07′28″E / 36.243443°N 118.124399°E / 36.243443; 118.124399). The Thousand-Men Cave was used as an arsenal by the Eighth Route Army from September 1938 to March 1939. Some of the major caves in the group have been made accessible to tourists as they are popular attractions.

Knight's Armament Company PDW and Yiyuan Rong Cave Group

As with all personal defense weapons, the KAC PDW is intended to be compact and lightweight (similar to submachine guns), but have a longer useful range (out to the low end of combat rifle ranges, 250–300 m).

Contents 1 Design 2 Ammunition 3 History 4 References 5 External links

Design

The KAC PDW combines new and off the shelf components in its design. The lower receiver, holding the magazine and trigger assembly, is essentially a shortened M16 rifle lower receiver,which makes the basic operating controls familiar to many potential users.

The cartridge, upper receiver, and operating mechanism are all new designs by KAC.

The KAC PDW uses a completely side-folding stock, unlike the M16 and M4 designs which have their main operating spring in a tube in the stock, and therefore can only partially telescope, and not fold sideways at all.

The KAC PDW is over 10 inches shorter (19.5" vs. 29.8" with stocks folded) and more than 1 pound lighter (4.5 lb vs. 6.3 lb) than the currently serviced M4 carbine, an U.S. Army and Marine weapon and the barrel has been lightened with a new dimpling process.

The KAC PDW has two gas pistons tapping hot gas from the barrel to operate its mechanism, located on the top left and right sides of the bolt carrier. The single mainspring is located on top, between the two gas pistons. Ammunition

The KAC PDW fires a 6×35 mm cartridge, a full centimeter shorter than the western military standard 5.56×45mm NATO round. The 6mm bullet is slightly wider, and the standard 6×35mm bullet is slightly heavier than the standard 5.56mm bullet (65 grains (4.2 g) versus 62 grains (4.0 g)).

Fired from a 10-inch (250 mm) barrel, KAC claims that the 6×35mm cartridge reaches a muzzle velocity of 2,450 ft/s (750 m/s), slightly faster than the muzzle velocity of a 5.56 mm cartridge fired from a similarly short barrel. The larger diameter, shorter 6 mm cartridge is optimized for these shorter barrel lengths, and would perform less efficiently from rifle-length barrels. The round's muzzle energy is 831 ft·lbf (1,127 J) versus 792 ft·lbf (1,074 J) for a 5.56 mm bullet, again from the same 10" standard barrel.

There is a discrepancy between the velocity claimed by Knight's for 5.56 mm 62-grain (4.0 g) SS109 NATO ammunition fired from a 10-inch (250 mm) Colt Commando barrel (2,400 ft/s (730 m/s), 792 ft·lbf (1,074 J) energy) and other M-16 manufacturers' stated muzzle velocities (2,627 ft/s (801 m/s), 950 ft·lbf (1,290 J)). In any case the energies and velocities are roughly comparable. History

The weapon was formally introduced at the 2006 NDIA Small Arms Symposium in Albuquerque, New Mexico. Some writers were shown samples at the earlier 2006 SHOT Show.
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