|
The 5.45×39mm cartridge is a rimless bottlenecked rifle cartridge. It was introduced into service in 1974 by the Soviet Union for use with the new AK-74 assault rifle. It gradually supplemented, then largely replaced the 7.62×39mm round in service. ==History== The 5.45×39mm cartridge was developed in the early 1970s by a group of Soviet designers and engineers under the direction of M. Sabelnikov. Further group members were: L. I. Bulavsky, B. B. Semin, M. E. Fedorov, P. F. Sazonov, V. Volkov, V. A. Nikolaev, E. E. Zimin and P. S. Korolev. The 5.45×39mm is an example of an international tendency towards relatively small-sized, lightweight, high-velocity military service cartridges. Cartridges like the 5.45×39mm, 5.56×45mm NATO and Chinese 5.8×42mm allow a soldier to carry more ammunition for the same weight compared to their larger and heavier predecessor cartridges and produce relatively low bolt thrust and free recoil impulse, favouring lightweight arms design and automatic fire accuracy.〔(Assault Rifles and Their Ammunition: History and Prospects by Anthony G. Williams )〕 The Soviet original military issue 7N6 cartridge variant introduced in 1974 are loaded with full metal jacket bullets that have a somewhat complex construction. The boat-tail projectile's jacket is clad in gilding metal. The unhardened steel (steel 10) rod penetrator core is covered by a thin lead inlay which does not fill the entire point end, leaving a hollow cavity inside the nose. The bullet is cut to length during the manufacturing process to give the correct weight. The 7N6 uses a boat-tail design to reduce drag and there is a small lead plug crimped in place in the base of the bullet. The lead plug, in combination with the air space at the point of the bullet, has the effect of moving the bullet's center of gravity to the rear; the hollow air space also makes the bullet's point prone to deformation when the bullet strikes anything solid, inducing yaw. The brown-lacquered steel case is Berdan primed. Its length makes it slightly longer than the 7.62×39mm case which measures exactly . The primer has a copper cup and is sealed with a heavy red lacquer. The propellant charge is a ball powder with similar burning characteristics to the WC844 powder used in 5.56×45mm NATO ammunition. The 7N6 cartridge weight is . Tests indicate the free recoil energy delivered by the 5.45×39mm AK-74 assault rifle is , compared to delivered by the 5.56×45mm NATO in the M16 assault rifle and delivered by the 7.62×39mm in the AKM assault rifle.〔(The Russians are coming! The Russians are coming! Or maybe the Polish by Holt Bodinson, Guns Magazine / Sept, 2008 )〕 Military 5.45×39mm ammunition was produced in the former Soviet Union, GDR and Yugoslavia, and is produced in Bulgaria, Poland and Romania. In the former Soviet Union this ammunition is produced in Russia, Kyrgyzstan, Uzbekistan and Ukraine. 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「5.45×39mm」の詳細全文を読む スポンサード リンク
|