This Instructable will hopefully teach you how to mod your Nerf Crossfire to be able to hold and use a magazine found in various other Nerf guns. Note that doing this will probably destroy your gun, however if done correctly, the gun should work but might not shoot quite as far. But who CARES! This mod will take about two days and doesn't require too many extra materials or tools.
-Hot Glue Gun
-Vice or Pliers
Step 1: Cutting
Cut out the front of the gun where the mag would go (pretty much where the pictures specify).
Step 2: Replacing the Compression Chamber
In this step you are going to have to cut open the cylinder located behind the bullet holder. You have to cut it so that it can accommodate the Nerf mag. Use the the little rod at the bottom of the bullet holder and glue it to the roof of the chamber. Put the cylinder back (but not the bullet holder) into the inside of the gun, then screw both sides back together.
Step 3: Magazine
This step will show you how to make a case for the magazine. Cut two square sheets of plexiglass 8.5 cm by 4.5 cm and another that is 2 cm by 6.5 cm, glue these sheets together into sort of a cube onto the circle where the bullet holder used to be. These measurements should be big enough to allow room for the magazine, but if not, you can just improvise.