Picture of Homemade Mini Coaxial Airgun
Well this is my instructable for my coaxial airgun that I put together.
It costs about $15 to construct, and is very fun to mess around with.
It shoots at roughly 600fps+ at 120psi with a .12gram airsoft bb and the excact specifications of the airgun made in this instructable.


And a couple tips (pretty much follow them or you will die,no joke)
*Never pressurize it over 140psi, even though it says rated to 480psi on the side.
*Never look down the barrel, even when you dont think it is loaded or pressurized
*Never aim at anything you do not intend to destroy
*Do not use this in an airsoft war, this is meant to just be something to mess around with. It will penetrated human flesh.
*Give the pvc cement and epoxy a full 24 hours to dry, no less.
*Have fun

Make sure you understand all those tips before going to next page.

And if you dont understand how a piston valve works then this is a helpful link.

Step 1: Getting Parts

Picture of Getting Parts
Well go to some hardware store and aquire all thse parts

1x 1/4in ball valve(metal)
2x 3/4in to 1/2in bushings(metal)
2x 3/4in female adapter(pvc)
1x length of 3/4in pipe of the desired size(pvc)
1x 1/2in copper cap
1x 6mm brass or aluminum tube of the desired length(might not be avaiable at your hardware store, try a hobby shop)
2x 1/2in to 1/4in bushing(metal)
1x 1/4in NPT schrader valve
3x 1/4in close nipples(prefferabley brass over steel)
1x double syringe container of epoxy
whatever tape strikes your fancy
bike inner tube

And some tools that you most likely have but if you dont you need to get them.

Adjustable wrench
Pipe wrench
A vice is helpful but not nesessary
A nail(or similar)

And that is it
If you dont have some of tools the project will be a lot more pricey.

ViperSniper4 years ago
awesome instructable, im gonna try making it this weekend.
$0m3_0n34 years ago
Where did you get the barrel? Is it the one from a walmart "shotgun"?
I found a workable tube at Hobby Hut. Any hobby shop is more likely to have the right size tube than a hardware store would be. Mine turned out to be an American standards measurement for diameter instead of 6mm, but it still works quite well since you don't need perfect fitting. Just bring a BB with you when you go and see what the smallest size is the BB will fit through.
The video cited for applying the epoxy is no longer on youtube and some pictures or diagrams of the piston in and out of the chamber would be helpful.
ive been shot by a 650fps full auto airsoft gun and now i have scars so dont shoot this at your friends cuz they will be PISSED! i kno u already said that up above but i just dont want anyone hurt or mad.
Message me when you figure out where you can get pvc
hardware store, warehouse
Very Cool! Great Instructable! Looks LIke a great gun. Now just make a hopper and loader for it and strap a CO2 tank to it and you have the most bad ass gun ever! Well done!
learn what a coaxial is, then you'll understand why you can't add a hoppper
there's a way, it's just hard to do
teapotking6 years ago
doesn't coaxial just mean it moves in sync with another gun? for example if a tank had a machinegun mounted on the main turret just to one side of the barrel, that would be coaxial. i'm not seeing any turret here... nice gun though
think like coaxial antenna wire. one around the outside of the other.... hence co-axial
do you have to repump it every time you want to fire it
evanwehrer6 years ago
This is really cool, when i make mine, I'm gonna use the air can from this instructable. And I may find an electric valve if I can find one wit the right size.
(Ill try to post pictures)
why did you remove all of your videos??
bigbob12345 (author)  thebluemartyr6 years ago
i didnt, my computor got hacked by some idiot and he got hold of some of my passwords, he then proceeded to mess up some of my accounts, including deleting my youtube account.
aerophyte6 years ago
Can you please post a video shooting the airsoft ammo and then one shooting liquid (loaded after pressure us applied)? Thanks!
from what i can tell this looks great! but i have no idea how to make it. NEED DIAGRAMS !!!!!!!! i REALLY REALLY want to make this! :P it would be perfect for my physics project (im designing body armour)
Mattrox7 years ago
great work very helpfull 3.5 rating
Mattrox7 years ago
how does the firing system work im stumped
bigbob12345 (author)  Mattrox7 years ago
Well there is a piston and you fill the air in behind it. This makes it move forward and seal against the barrel. And when you exhaust the air behind it with the 1/4in ball valve the air infront of it pushes it back very fast and goes out the barrel. I probably should have included some animation in it. If I get the time I will make one but if not I'll just add a link to something helpful
bigbob12345 (author)  Mattrox7 years ago
Well I didnt get the chance to make a animation so I just posted a link to an animation made by someone else. Hope it helps you understand it.
Mattrox7 years ago
awesome bigbob12345 but could you add some boxes naming the parts pleaz
bigbob12345 (author)  Mattrox7 years ago
I'll do that right now
cool looks great
nice one mate in the intro at the end of the list of things to 'pretty much follow or you will die' you said have fun...haha 'have fun or you will die' i like it!!
Sgt.Waffles7 years ago
Sick as! Good on ya!