F.E.A.R

Double Machine Pistol Glitch.

Here's how to get infinite ammo for your double machine - pistols.

1. Have 2 Machine-Pistols with at least 1 bullet (better if there is more)
2. Find another weapon that is not already in your inventory.
3. Swap for that weapon then swap back to the machine-pistols. 
4. Now you will keep doubling up ammo until you reach max 600