This is a project i am currently working on - spring powered BB/Dart gun. Requires Spring, Metal/PVC pipe (Whichever you feel more secure with, i chose metal), Metal barrel, I chose 4.5mm .77 barrel from an old airgun, spring, some cutting of wood, and dowwel. This is alot more powerful than other bb guns powered by combustion, bike pumps ect. so be carefull.

Step 1: Materials

Airgun Spring - Check your local airgun shop, or if your australian, find one.

Wooden circles, cut with a hole saw

Metal tubing, to fit your spring.

Endcap for the tubing

4.5mm copper, or any other metal tubing for barrel, 4.5mm is .177 for metal bb's or airgun darts, although if you wanted to fire plastic bb's you will need 6mm tubing i think.

Metal dowwel

I think thats it *thinking face*

Step 2: First Step (not Really Step Two)

See picture, you only cut into one side of the piping, dont go all the way through

Step 3: Step Two

Add your spring to the tube

Step 4: Step Three

Now, put a holesaw on your drill with 4mm drill bit in and whatever holesaw bit you need to fit your spring tube, it has to be able to move in there, if need be file it down a bit if you dont have the right drill bit.

Then, throught the hole in the middle, glue the 4mm dowweling in.
Screw a screw in the top of your circle, the slide the screw down your cutting in the springtube, therefore compressing the spring, and then twist to the side, locking in place, this is how you cock your gun.
Put this in your spring tube.

Step 5: Step 4

Now copy step three, but put a 4.5mm drill bit in your drill with a little larger holesaw bit, this shouldnt move in the spring tube. drill your circle out.

INstead of dowweling use 4.5mm (hollow!) copper/metal pipe do not block it off at all, this is your barrel

Glue the hole thing onto the other end of your tube, like an endcap. all done:)

Step 6: Tripple Barrel and Body.

Triple Barrel

The picture below shows how to add tripple barrel, just change step three, drill three holes in the wooden circle and put three pieces of dowwel in, also, change step 4, to 3 barrels

Body
For the body, be inventive, it all depends on the size of your spring/spring tube, mine is going to be around 16" i think so i am going to build it as a sawn off shotgun.

Convert to real gun

Ok, i think this would work, as it is basically a much more powerful zip gun (powered by elastic band).
You sould just be able to sharpen off the metal dowling with a dremel/file, until it is about as sharp as a sharpened pencil.
Change the barrel to whatever size bullets you want it to take ...8mm, 9mm .22, whatever.

I havent tried doing this but i think it would work.

Any questions or comments please email-: Camster911_190@hotmail.com
I have a website coming soon.