Instructions
Turn on your gaming console or gaming computer and insert the "Call of Duty: Modern Warfare" game disc. Wait for the game to start. Select your user profile to access your own saved game data, then click "Start."
Search for enemy intel while playing the levels; the intel looks like black laptops. Simply run to the intel to pick it up. You must collect all 30 laptops. If you've already played the game through once and don't want to waste your time searching for the laptops, utilize an "Enemy Intel Guide," which tells you the location of all 30 objects.
Click "Start" and go back to the main game menu. Select the "Cheats" menu, then click on your newly-unlocked "Infinite Ammo" feature for unlimited ammunition.