In summary, each new Weapon Platform has weapons of different categories (Assault Rifles, Battle Rifles, SMGs, etc.) in that single platform. By default, one weapon within each platform is already unlocked. You can unlock the rest of the weapons by leveling up the default weapon to reach a specific level, at which point the Receiver for the next weapon will unlock. The Receivers essentially convert your weapon into a completely different weapon. Some weapons require you to unlock weapons in a different Weapon Platform before you can unlock them. This going back and forth between platforms can be confusing. The new UI in Modern Warfare 2 doesn’t make it any easier to navigate the weapon platforms. In this article, we’ve listed all the weapons and their respective Weapon Platforms, Receivers, and unlock requirements, so you can easily identify what weapon you must level up to unlock the weapon of your choice. We’ve separated each table into a specific category (Assault Rifles, Battle Rifles, SMGs, etc.). The tables will be updated as well get more weapons in the future seasons.

Assault Rifles

Battle Rifles

Marksman Rifles

LMGs

SMGs

Handguns

Shotguns

Sniper Rifles

Launchers

All Base Weapon Unlock Requirements  Receivers  in Call of Duty  Modern Warfare 2 - 18All Base Weapon Unlock Requirements  Receivers  in Call of Duty  Modern Warfare 2 - 25