The title is pretty self explanatory.
Once again, sorry about poor photography. this was taken at like 10 at night.
If you can't see, the two black pieces at the bottom are this and this
Step 3 I love using this design for the butt stock of guns
Step 4 Those are 2-long and 4-long axles respectively
Step 5 This finishes the first section of the gun
Step 7 That is a 3-long axle if you didn't already figure it out
Step 8 Here's where the hinges come into play
Step 9 Make sure that the hinge is two clicks above horizontal
Step 10 Connect the first two sections
Step 12 The beginning of section 3
Step 13 Pay no attention to the unidentified green object
Step 14 If you can't figure out what axle size that is, then just leave.
Step 18 If you can replace the light grey pieces with black, I would recommend you do so.
Step 19 Bringing it all together
Step 20 The finished product
Demonstrating the function of "reloading" it
That's about it. You can use the design. just be sure to give credit where credit is due.