You could try to install a device that would hold on to the ammo, but release it at full pressure, acting as a burst disc of sorts. My old cannon had a rubber washer epoxied onto the barrel, which would hold the ammo, power was very impressive too, >600fps with 6mm .2g bb's. http://www.spudfiles.com...

For plastics: white lithium grease
For rubbers: light silicone oil
For metals: Militec-1 (synthetic weapons lube, love the stuff)

I know I don't necessarily need to use hose barbs. But I don't know if I'm going to use .40" or .50" blowgun darts for my cannon. Ill need to buy samples of both darts and see what kind of metal pipe fits which dart best, I wouldn't trust the thin-walled blowgun barrels on a 400-500 psi cannon. So h...

I went to Lowes today with your parts list, wanting to make a slightly downsized version of your piston valve for my -in the making- blowdart gun. But as I was searching for the right hose barb I noticed that the hose barbs at my lowes were very different than the one you got. They didn't have any m...

That would totally never pump to ANY useable pressure.

If the second set of washers apparently doesn't seal 100% and a equalization hole can be put there, then what is the point of them? If im understanding this design fully, then couldnt it work just fine with just the hose-barb sealing gasket on the front of the piston? Or is there a purpose in trying...

I have thought about this before, staring at my stash of 2-3um aluminum powder and then my cannons. I was thinking if you could make an aluminum powder laden burst disk, then pressurize with air until bursting pressure (aerosolizing the aluminum), and have the burst disk burst into a chamber contain...

Didn't BTB talk about a QEV mod which serves the same purpose in some other thread?

edit: BTB already mentioned it a few posts up... whoops

Trrrant: I really should stop at a auto-zone to take a look, but im almost positive the Lowes near me sells at least 1/4" rigid copper pipe. I remember considering using it for This cannon, but opted for a tightbore airsoft barrel. I ran into that ebay bearing shop a little while ago and have been l...

I have been curious about the QEV/popoff combo for a long time now, and since recently it was proven quite effective, I have decided to jump on the bandwagon. I have all the plans for this cannon drawn out but the only thing that is holding me back from start buying parts is the need to find a suita...

None of those toys have anything on the Venom. While I thinkthe Venom is pretty sweet, I don't think it will throw 7lb projctiles 3 miles, or 300lb projectiles at 1000fps.... And if it could, I would want to be holding it to fire it... :wink: A quick switch to a larger barrel will sove these proble...

the fill valve is an airsoft gas gun magazine fill valve. I got mine from an old magazine. You can buy extra refill valves though: http://www.redwolfairsoft.com/redwolf/a ... odID=26229

The thing at the end of the syringe is the nozzle of a butane can, epoxied on.

hmm so when you load it you put it in the chamber, fit it the washer and then put the swan neck thing back on? pretty sweet cannon Almost, the rubber washer is epoxied to a larger metal washer all epoxied to the breech end of the barrel. So when I load it, I just push a bb into the rubber washer at...

Bah, silly people. Just do what professionals do. Before she goes to sleep tell her you want to rub lotion on her. Mix up some 5 minute epoxy and smear it on her back. She goes to sleep then bamn! Then repeat till she cracks on. I'm mildly disturbed. Damn. I can't get that kind of power out of any ...

UPDATE I took another shot at a can, to see what velocity the bb's are traveling around (poor man chronograph style). If a .20g bb can go through the bottom of a can it is estimated to be going 420-450fps, through the top: 520-540fps. Well, much to my surprise, when I shot the can in the bottom, it ...