SpudFiles

I just bought a piece of 1/4 brake line as the barrel for my pellet gun. My problem is the 4.5 mm pellet/bb fits loosely and has a gap, will putting wadding behind the pellet yield decent power compared to a perfect sized barrel. Also at a 100psi is it possible to get decent power from a pellet in a piece of 1/2 inch copper pipe as the chamber. It will be a coax. I plan to use a blowgun to pilot it. Ill probably cast a epoxy piston.

A .5 in. chamber and a .25 in. barrel on a co ax doesnt leave a big volume unless its really long. Also the wadding will definately help, you just need a ramrod.

Gun Freak wrote:A .5 in. chamber and a .25 in. barrel on a co ax doesnt leave a big volume unless its really long. Also the wadding will definately help, you just need a ramrod.

If you are going with such a small chamber volume, and are doing it in copper pipe, why are you limiting the pressure to only 100psi? GGDT will make a prediction for you, but I can just about bet that you will not be satisfied.

From experience, you wont be happy with the power. I wouldn't want to be shot by a BB at 100PSI from such a cannon, but power will seem pretty pathetic. You'll still shoot through a soda can though.

MrCrowley wrote:From experience, you wont be happy with the power. I wouldn't want to be shot by a BB at 100PSI from such a cannon, but power will seem pretty pathetic. You'll still shoot through a soda can though.

Would a larger chamber volume increase power for a cannon on a coax this size.
And to Hubb
I am limited to 100 psi because I only have a cheap bike pump

A larger chamber will, in fact, increase the power, as long as the barrel is of the right size. As far as your bike pump, consider an upgrade.

make the chamber a bit smaller and get a shock pump, at 300 psi you want be disappointed at the power. make sure if you ram wad and ammo down that you stop it going into the chamber

Hubb wrote:A larger chamber will, in fact, increase the power, as long as the barrel is of the right size. As far as your bike pump, consider an upgrade.

Couldn't agree more, the smaller you go with calibre the more you need to up the pressure to keep the power up. Remember that to have the same power potential as a 1/2" barrel at 100 psi, a 1/4" barrel needs 400 psi.

A shock pump is a cheap and useful source of 300-400 psi for a small chamber, and if you have access to proper epoxy making a small piston cannon should be no problem at all. You could very easily take this design and make it longer.

jackssmirkingrevenge wrote:

Hubb wrote:A larger chamber will, in fact, increase the power, as long as the barrel is of the right size. As far as your bike pump, consider an upgrade.

Couldn't agree more, the smaller you go with calibre the more you need to up the pressure to keep the power up. Remember that to have the same power potential as a 1/2" barrel at 100 psi, a 1/4" barrel needs 400 psi.

A shock pump is a cheap and useful source of 300-400 psi for a small chamber, and if you have access to proper epoxy making a small piston cannon should be no problem at all. You could very easily take this design and make it longer.

I might see about upgrading to a shock pump and I my switch to a 1 inch chamber and a tee valve http://www.spudfiles.com/forums/high-pr ... 19694.html like this, because I dont want to deal with copper and I can screw all these parts together