Gas Sampling Cylinder Paintball Rifle

[Tetsuo315]

This is the first noob cannon I ever built. I had my doubts though when I was in the planning stages. I did not think I would be able to use the gas sampling cylinder for the air chamber. As luck would have it, the cylinder uses NPT threads. That allowed me to use compression fittings, quick connects, and a pressure gauge. The cylinder was MFG. by Precision Scientific Inc. of Chicago. My father brought three home one night from an oil refinery he used to work at in Ohio. These devices can handle pressures in excess of 1000 psi. I felt that it would make a nice chamber as long as I kept the ratio proportionent. Unfortunately the PVC fittings and sprinkler valve can't take pressures that high. No more than 145 psi (if that) on the valve. When using GGDT to find out the power of the rifle, I was not sure what values to put in for my sprikler valve. So, I used the specs of the 1" valve off of the GGDT site. I lowered the flow efficiency rate for my Rainbird(Rainbirds tend to open slower than Watermasters) and pluged in the specs for my valve that I could find out. Here is a partial GGDT result. See pic for full specs:

Chamber 2.0265"ID X 10.1875"L
Barrel/Bore (.695"ID Approx.) X 42"L 3/4 CPVC
PB Projectile 3 Grams .690"D + or -
135 Psi/9.6 Bar
812 Ft/s
67.9 Ft*lbs Kinetic Energy

I think that the muzzle velocity here from GGDT is somewhat optimistic. I will have to wait until I can get a hold of my Grandfathers chronograph to be certain. A Couple things I learnt when making this. A Sprinkler valve makes a nice LOUD!! air horn. This is a fun hobby if not taken for granted.

I noticed that the basic Husky blowgun(8 bucks @ Lowes) needs some modding. The sprinkler valve mod how-to says to use a 1/4" NPT nipple or hose barb. If you use a 1/4" nipple in conjuction w/ a Husky blowgun, your pilot hole goes from 1/4" down to 1/16". Thats still ok If you use a small bore barrell, otherwise it will honk. So I widened the ports in the blowgun as close to 1/4" as possible w/ a drill press. That solved the lovely honking. Well here are few pics of the rifle and some damage done with a paintball at high velocity.

This is the coolest sight I have ever visted. The rifle would not have been possible without this resource.

[)DEMON(]

THAT IS AMAZING!!and you certainly know what your talking about, that cannon is great. How do you hold it?
I expect to see plenty cool cannons from you.

[CS]

Nice and clean! Even more powerful. The metal chamber makes it look very clean. This by far doesnt look like a first cannon... That damage to the acrylic is amazing! Like Demon said, surely stick around the hobby. Im very suprised at such a new member with good grammar, you know there is members with over 200 posts that still cant spell 3 letter words and/ or capatalize...

[Tetsuo315]

Thanks for the comments. It is indeed my first cannon. There are a few flaws that need some working out. After the chamber has been charged, there is a very small leak. It may be inside the valve. I have opened it several times for modding, so it might be PVC dust or other fine debri. I might leave the leak though, and use it as a slow discharge for saftey reasons. Second CPVC at 42 inches in length is not too rigid. I'm thinking about sleeving a new barrel for use with PBs.

There is a 3"D X 15"L PVC Chamber waiting to be pressure tested for use with this cannon. I could not do this project without making a homebrew chamber. My first PVC chamber had a leak(forgot to give the fittiings a 1/4 twist). Found yet another resource here at Spudfiles for solvent welding. So we will see what happens.

I use the white fitting just before the barrell as a forearm. My trigger hand rests with the shape of the blowgun and ball valve. Sort of like an M-16 or PSG-1 sniper rifle. I'm thinking about adapting a wooden pistol grip and forearm to the cannon. This is definitely a new hobby in the making for me.

-tetsuo315

[frogy]

Im very suprised at such a new member with good grammar, you know there is members with over 200 posts that still can spell 3 letter words and/ or capatalize...

lol.... still can spell 3 letter words...

I think you mean can't... pimpman makes boo-boo's too



I really love this cannon, like the others say, definately keep in touch with these forums, I think that looks amazing with the metal chamber.

[x.X.Cpt.Rollhart.X.x]

very nice cannon, but you cant freeze a paintball, the paint inside is a kind of oil, the only part that u can freeze is cockle but it make them more fragile.

[)DEMON(]

tetsuo315, I had the same problem, there was no problem with the diaphram, it was the female threads on the sprinkler valve. I had to use quite allot of teflon tape to seal it properly, I also had to epoxy around the point where the brass adapter was screwed into the top of the diaphram. If you still can't find the leak make sure you have put enough teflon tape on your threads.

[sgort87]

Sticking a paintball in the freezer will not freeze it as Rollhart said, but it will still cause more damage. The molecules in the ball are slowed way way down when cooled. If you can launch them without breaking the shell right away then these will cause more damage.

BTW: it's FISH oil.

[Tetsuo315]

Oh, Ok. I wondered why the PB was not rock solid. Fish oil? Then it would be more or less a gel at that point.

[CS]

I froze my paintballs and they dimpled up and when shoot out a cannon traveled just about the same distance in the X-Y axis as they did the Z axis. (From the shooters prospective)

[noname]

Thank-you! Finally, someone who has never built a cannon before builds a pneumatic first! Everyone says they built a combustion first because of their simplicty but that's BS. Pneumatics can be equally simple and much more powerful.

[)DEMON(]

I have never build a combustion.

*by the way did you all see my HK1?

[frogy]

I think ball valves are easier to make than a combustion

Sprinkler Valves aren't very hard at all

Coaxial Pistons are soo easy if you know how to make a diaphragm.

I keep looking at this gun, then not saying anything about it, I think it looks cool, people type to much about it and me short attention span explodes

[rna_duelers]

Nice cannon and gettting to mach 0.7 is nice. Gota love the clean look,i swear thats gunna go on the official cannons in no time .Maybe get a metal exhaust valve n brass fittings and get it to 300psi and watch the PB's fly.

[Tetsuo315]

Some improvements have been made to the rifle!! In a few days I will post some pictures for you all to see. Semi auto with blowback