This mod will teach you how to make your rampage be a single shot but still retain the ability to use a mag. The reason for this is simple. Using a mag chews up your bullets, and the rampage jams easily.
Step 1: Take Apart
Just take it apart
Step 2: Sawing
Now take the piece with the metal rod and cut off the bit in the second pic.
Step 3: Loading
Now put it back together and your done! To load just half cock the gun and pull back the jam door and insert bullet.