Note: The grenade launcher has a block trigger but since this is more of a secondary, special, or back-up weapon I guess it doesn't matter as much.
More Instructables by me.
Step 1: Making the Components
Picture 1: Make 2 (Lets for now call these part A).
Picture 2: Make 1 (Lets call this part B).
Picture 3: Make 1 (Lets call this part C).
Picture 4: Make 1.
Picture 5: Make 1.