The K-87 is an ultra compact version of the K-86 with a heavily modified reciever and ultra short barrel and modifeied stock equipped with the same scope as the K-86.
Some versions of the K-86 come equiped with the K-77 grenade launcher. It fires low velocity 40mm grenades such as HEDP, Smoke, Flechette and chemical rounds. It is based off the K-203 the licence built version of the M203 grenade launcher but heavily modified. Its ultra compact size prevents it from firing standard 40mm grenades so it has to use special 40x43mm Low Velocity Ammunition.