SpudFiles

It may look small but this cannon packs a punch. I designed it to ba be a nice, quiet plinker. The chamber is extremely small and that means that it only takes two pumps from my big bike pump and around six from my small pump to get it to a decent pressure, even though I mostly use my propane pneumatic fill setup now.

Here are some specs:
-20mm x 10cm chamber (tiny I know)
-6mm x 65cm barrel
-20mm sprinkler valve
-Handmade wooden stock
-Nikko 3-9 x 40 scope

EDIT - The videos are here (sorry about the quality).

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Charging the gun with my propane pneumatic setup

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Firing the gun after charging with propane

that is such a sweet gun i love it the barrel and friends just need a coat of paint and it would look insain
great job on the engraving

im halfway through building a gun like this but it wont b ready for the comp

you're going to have to set the videos to "public" as opposed to "private" if you want us to see them...

Thanks for the heads up.
Videos are now public.

That's better

How do you know how much pressure you're putting into the chamber?

You can work out the pressure of propane inside your chamber using this table.

Around here it is probably averaging 20oC this time of year do I am getting around 110psi.
I'll put up a thread this weekend on the propane setup.

Very nice man.

now my question...

when you fill does your chamber actually contain liquid propane from being compressed?

Because there is a 20% (I think) vapour space in the tank there shouldn't be any liquid in the chamber, because most of the expanding is done in the tank only vapour should come out.

That gun is awesome. I am surprised that you can get so much power out of such a small chamber. And that fill setup ain't something you see everyday. Good job

SAWEEt thanks man, semi-auto s400 comin 2moz (if all goes well) 8)

I would only suggest a coat of paint for the barrel and tripod.
Very nicely done mate, but then again.. duhh... he's aussie

What colour do you guys reckon I should paint it. I'm thinking either Woodland Camo, Urban black or a Walnut stain. The barrel is gonna be either Matte black (cant go wrong) or I might try Woodland on the barrel as well as the stock.

Paint over that wood-burn job...? I was just suggesting that you paint the barrel but if you are going to give the whole thing a paint... woodland would be the best. Although I do like the burn pattern you did so personally i would go the stain and give the barrel a matte balck. GOGO before submissions close!

You have inspired me to build myself one of these. how accurate is it with those bb's? they look like 1/4 inch steel slinghsot ammo but then your an aussie so......... those might be illigal there

i found on mcmaster .25 cal high polish steel bearings for 5 bucks (.0001 in tolerance) and for 20 bucks 48 inches of stainless steel tubing with a .251 ID. (tolerance, .001 inches). i have a feeling this will make my gun quite accurate. im thinking a piston valve, however, but i really like that wood frame yuve got on that. might have to steal that...... KIDDIng. ill make myself something different. but otherwise, this gun is what i like. small calibre, high power, and realistic.

kudos........

Seeing as your chamber is so small, there is ample space for another. Have you considered putting a second chamber behind it with another valve? That way you could get two shots per charge.