This instructable is on how to make a home made BB gun out of very commonly available parts, i have spent ages researching and developing this design to make a cool Christmas present for someone.
I was in the progress of making a home made paintball gun, but the practicalities of it were just stupid. So with a little modification i made a much better BB gun!
Warning: This thing is VERY powerful even with a moderate pressure of 50PSI.
Step 1: Make the gun/barrel
First of all you're going to have to find a garden spraygun with a removable head set up, preferably it must have the trigger in front and be able to release air pressure very rapidly.
Amazingly i found a PVC component that screws exactly onto the spraygun.
The next component is a piece of 21.5mm PVC pipe with a garden hose quick connect thing glue inside.
The alu tube of 6mm or close as possible internal diameter (the closer the more powerful) friction fits with a piece of sticky tape inside of the quick connector.
The length of the barrel has a big effect, the longer the more accurate your BB will travel but at a risk of slowing it down over the length and the shorter it is the faster it will travel withing reason.