The K-1A3 Mod 1 is a SBC (short barreled carbine) designed for use in an urban environment as use as a primary service rifle to be used in conjuntion with 5.56x45mm rifles and as a close to medium range marksman rifle. This variant is equipped with a 27 round extended magazine and a retractable stock.
The Mod 2 variant includes a fully automatic fire selector for use in close quarters but it is usually only fired in semi auto mode and the Mod 2 is ussually given to special forces and Marine units.
The K-1A3 is issued with an ACOG sight or iron sights this version is equipped with iron sights as it is to be used as the a standard service rifle instead of a marksman rifle.
The benefit of using a 7.62x51mm firearm with 5.56x45mm firearms is that it can provide superior penetration.