SpudFiles

Today i am going to my hardware store to buy ten feet of 3/4" pvc pipe. I am wondering how much of that can i use to make a barrel for a pneumatic using a modded 3/4" sprinkler valve. My chamber is 12" of 1.5" pvc pipe. Size is not an issue and i want maximum power. My current barrel is 30" of 3/4" pvc pipe.

On that bolt action I posted a while back, I used a 2 to 1 chamber to barrel ratio and GGDT said I had speeds approaching 700 fps.

should i just leave my barrel as it is because its close to 2:1 right now?

It depends, right now I have a longer barrel on it, probably close to 3 ft and it honks like a goose. So if you want it quiet I would say go as long as possible.

But going longer will increase power? Am i right?

Yes but there will be a point where it just becomes impratical.

I have two usually, one about 90cm/3' and another around 135cm/4.5'.

Depends on what i'm going for, accuracy, power, portable, ease-of-use etc, so just make two if the pipe's cheap enough.

I just bought a ten foot piece of that stuff today for like 6 bucks, so why don't you make two different barrels and experiment?

With a chamber that big, you can use as long a barrel as you can get a continuous length of pipe in. If you want it to be fun and practical, use whatever length seems the most comfortable. I'm not into the low power low pressure cannons enough to know much about them, but I did build a really ghetto 400 psi handheld burst disk gun (.787" bore, 30ci chamber), and the 5' barrel seemed just about right, and fairly comfortable to shoot (apart from the mild - medium terror resulting from firing it without knowing when it's going to shoot). That barrel was copper though. For PVC, you'll probably have to have an external barrel support if you want a decent sized barrel in such a small bore.

Ill just cut the biggest size that wont bend and would be fully self supportive