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.
Step 2: High Pressure Tank
The high pressure tank can hold about 120PSI, it is obviously made out of an old PET drink bottle.To make the connection on the lid you have to make a hole the size of the shoulder of a quick connect coupling and cut away the rest of the coupling that doesnt fit in the lid, then put washers to completely seal it. The hose and connectors: the first connector is just a normal one but the end one has got a valve so when u disconnect it from the filling station it all stays in the vessel.
If you can afford to, rather get the brass connectors they can hold alot more pressure without leaking, and you will have a much more reliable system.
Step 3: Temporary Containment Vessel
The purpose of this tank is to hold the pressure of the big tank but in a very small volume.So the valve would be used to charge this small tank then that valve is closed and then the trigger is pulled and this small volume of high pressure gas exits the barrel taking the BB with it. The smaller the volume of air the less air you use out of you main tank. I have added water so this is adjustable, hence water is incompressible.
Step 4: The Valve
The valve is just a standard three way used for splitting water to different hoses from one tap.To use the gun open the valve from the main supply tank and this will charge the temp tank with air, close the main tank and fire.
Step 5: Make a Main Tank Pressurizer
the pressurizing station consists of a two way quick connect connected to a quick release this has a hose and a schrader valve for filling from a car pump.Simply connect the main tank onto this and recharge, each tank should give you about 50- 70 shots at 120 PSI.
Step 6: Be Careful!
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