Step 6: Assembling
To stabilize the plastic, glue one washer to the back of each hole, as shown in the first picture. Then secure the connector pieces with a screw and two nuts each.
Reassemble the gun, if you are having trouble on finding the correct spot for every piece, check out the picture in step 2. If you would like to make your gun stronger, add two or three washers at the back of the spring.
Once, you are done, you will have to reassemble the barrel. Instead of using the small grey front piece, use the front connector piece, as shown in the third picture. Don't forget the spring and hammer the metal rod back into the barrel. Once you finished one barrel, turn the mechanism and attach the next one.