|Feeding and cartridge|
The SGI 5.45 is a unique variant of the SIG SG-550 which was modified to chamber the more common 5.45x39mm cartridge. The weapon remains only in Clear Sky's game files and was probably added before the developers decided to add the weapon upgrade system into the game. This weapon is now redundant since all SG-550s can be modified to chamber 5.45x39 rounds with the caliber change modification.
"Some crafty folk have modified the SGI 5k to work with the Soviet round, which is more common in the Zone, all the while retaining the rifle's ability to use any of the base model's modifications. Uses 5.45x39 mm ammo."