Mensaje por IVAN-HK » 09 Ene 2008 17:56
A 5.6x45 cartridge, designated as the GP90, was adopted. Despite the 5.6mm designation, the Swiss round is interchangeable with NATO 5.56x45 rounds.
Unlike the current NATO which is optimized for a barrel twist of 1 in 7", the GP90 round is optimized for a 1 in 10" twist. This was done to optimize ballistic, accuracy and barrel life. The GP90 also lacks the steel core used by NATO rounds, rather it uses an lead core. The GP90 was originally clad with a nickel jacket, however, this was found to cause excessive barrel fouling, so in 1998 the nickel jackets were replaced with copper jackets. In addition, in 1999 a copper plug was added to the base of the bullet to address environmental concerns.
A 5.6x45 cartridge, designated as the GP90, was adopted. Despite the 5.6mm designation, the Swiss round is interchangeable with NATO 5.56x45 rounds.
Unlike the current NATO which is optimized for a barrel twist of 1 in 7", the GP90 round is optimized for a 1 in 10" twist. This was done to optimize ballistic, accuracy and barrel life. The GP90 also lacks the steel core used by NATO rounds, rather it uses an lead core. The GP90 was originally clad with a nickel jacket, however, this was found to cause excessive barrel fouling, so in 1998 the nickel jackets were replaced with copper jackets. In addition, in 1999 a copper plug was added to the base of the bullet to address environmental concerns.