page_title: 5.56×45mm NATO
section_title: 5.6mm Gewehr Patrone 90
hierarchical_section_title: 5.56×45mm NATO / Military cartridges / 5.6mm Gewehr Patrone 90
caption_attribution_description: English: Swiss Army Gw Pat 90 tracer rounds (591-1055). Français&#160;: GP 90 Cartouche lumineuse (591-1055).
context_page_description: The 5.56×45mm NATO is a rimless bottlenecked intermediate cartridge family developed in the late 1970s in Belgium by FN Herstal. It consists of the SS109, SS110, and SS111 cartridges. On 28 October 1980 under STANAG 4172 it was standardized as the second standard service rifle cartridge for NATO forces as well as many non-NATO countries. Though they are not entirely identical, the 5.56×45mm NATO cartridge family was derived from and is dimensionally similar to the .223 Remington cartridge designed by Remington Arms in the early 1960s.
context_section_description: The 5.6mm Gewehr Patrone 90 or GP 90 (5.6 mm Rifle Cartridge 90), is the standard round used by the Swiss military in its rifle, the SIG SG 550. The cartridge is also known as the Cart 5,6mm 90 F (French: Cartouche pour Fusil / Italian: Cartuccia per Fucile) to the French- and Italian-speaking Swiss militiamen. The Swiss refer to the round as the 5.6 mm Gw Pat 90, although it is interchangeable with the 5.56×45mm NATO and .223 Remington round.  The Gw Pat 90 round firing a 4.1 g (63 gr) FMJ bullet is optimized for use in 5.56 mm (.223 in) caliber barrels with a 254 mm (1:10 in) twist rate.
  The Gw Pat 90 was designed for the SIG SG 550 when it came into production in 1987, replacing the SIG SG 510. Previous experience of a change in standard rifle had proved that changing the distance of fire for the training ranges was more expensive than the design of a new ammunition; this prompted the design of a cartridge nominally capable at 300 meters. The cartridge was also designed to reduce pollution by controlling lead emissions. The bullet was originally clad with a nickel alloy jacket, however, this was found to cause excessive barrel wear, so in 1998 the nickel jackets were replaced with tombac jackets. In addition, in 1999 a copper plug was added to the base of the bullet to address environmental concerns.
  The ammunition is currently (2009) produced by RUAG Ammotec, a subsidiary of the RUAG group. The ammunition is manufactured in three variations: the standard FMJ round, the tracer round, and a blank round.
  The FMJ cartridge has a Copper-Zinc alloy case and uses a double base propellant. The bullet is a 4.1 g (63 gr) tombac jacketed FMJ projectile with a G1 ballistic coefficient of 0.331 (ICAO) / 0.337 (Army Metro). The projectile contains approximately 95% Pb, 2% Sb, 3% Cu, and was designed for terminal ballistic instability. The required accuracy for Gw Pat 90 ammunition out of factory test barrels is 63 mm (0.72 MOA) for 10 rounds (100% radius measurement method) out to 300 m. The Gw Pat 90 cartridge dimensions are in accordance with the civilian C.I.P. standards for the .223 Remington C.I.P. chambering.
  The Gw Pat 90 is used both in the Swiss military and in sport shooting. The very high level of individual training in the Swiss militia (every single soldier bearing a weapon has to shoot in order to maintain his ability once a year; see Gun laws in Switzerland) and the overall use of the Gw Pat 90 by the many Swiss citizens who shoot in competitions and for amusement has resulted in significant input on its usage. Over 1 billion cartridges had been produced as of 2005.
caption: Swiss Army Gw Lsp Pat 90 tracer rounds
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