References to unreleased weapons have been found in the Call of Duty: Modern Warfare PC files by @MrJaRnii.
The two weapons that have been discovered in the PC files are the Vector SMG, which was in previous Call of Duty games, and a Crossbow weapon.
The Vector SMG:
In addition, fans have also found references to the Crossbow in a poster on one of the maps in Call of Duty: Modern Warfare. This was found by@ bxttxr_off_dxad.
Infinity Ward has not announced when new weapons will be added to Call of Duty: Modern Warfare. Activision has confirmed that new weapons will be “earned through gameplay” in Call of Duty: Modern Warfare and not locked by RNG in this title.
We’ll update as we learn more.