The Kastov 762 assault rifle in Warzone and Modern Warfare 3 is a weapon many players of MW2 may have already unlocked. Initially featured in Modern Warfare 2, this gun is essentially the classic AK-47, entirely unlockable and usable in Modern Warfare 3 by all players.
The Lachmann-762, a select-fire battle rifle in Warzone 2, takes inspiration from the real-life Heckler & Koch G3.
