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Bolt Action Rifle run on Propane

Posted: Wed Apr 14, 2010 6:57 pm
by spudnutbutthut
Hey everyone, I have made a pretty successful C02 bazooka that runs on propane, with a leveled out bottle of gas it takes about 2 minutes to get to 45psi and then fires nerf vortexes like a champ. I want to try something new now, but im not very good with the tolerances of pressures, how to create perfect pressure and chamber to barrel ratio etc.

I have a few questions:

If I want to fire a .3g BB at 45 psi, to get to about 450-500 fps, what size chamber do I need? The barrel will be about 455 mm long with a 6mm diameter (inner), what would be an optimal ratio of chamber to barrel, please note I want to use a 3/4in sprinkler valve with blowgun. Unless there is a better way to make this. Im a bit of a noob so i need either some help or a link or two, cause all i see is 700psi cannons that fire metal ball bearings! OUCH!

Also how might a have a constant connection directly from the tank, but still be able to regulate the pressure without venting?

Re: Bolt Action Rifle run on Propane

Posted: Wed Apr 14, 2010 7:21 pm
by jackssmirkingrevenge
spudnutbutthut wrote:all I see is 700psi cannons that fire metal ball bearings! OUCH!
It's called "progress" ;)

As to your requirements, a sprinkler valve is probably overkill. Blowguns alone can give pretty good performance ;) though since you're using such low pressure, you're probably better off with a 1/8" or 1/4" Quick Exhaust Valve, with a momentary pilot that will give you good semi-auto performance.

Posted: Wed Apr 14, 2010 7:27 pm
by iknowmy3tables
why is it called a CO2 bazooka if it runs on propane?

Posted: Wed Apr 14, 2010 8:13 pm
by spudnutbutthut
LOL!, i dunno why i put Co2 in there. Could you maybe post an example of what jack described?

Posted: Wed Apr 14, 2010 8:44 pm
by clemsonguy1125

Posted: Wed Apr 14, 2010 10:38 pm
by spudnutbutthut
hmmm, im bad at visualizing, what would be a good piston to use ? I want to make it bolt action so, a coax? I heard there was something bad about coaxials...hmmm, i just want whatever will be most accurate with a velocity around 450fps, is there anyway to use a program to determine speed of projectile with the chamber size and pressure, barrel size etc?

Posted: Thu Apr 15, 2010 12:06 am
by jackssmirkingrevenge
spudnutbutthut wrote:is there anyway to use a program to determine speed of projectile with the chamber size and pressure, barrel size etc?
Have a play with Gas Gun Design Tool ;)
I want to make it bolt action so, a coax?
Not a good idea for bolt action as the section of the barrel where the bolt should be will be enclosed in the chamber.

One of these and you're sorted ;)

Posted: Thu Apr 15, 2010 2:48 pm
by spudnutbutthut
cool, but how would i use a QEV? I have 0 clue about pistons and how to make one even though ive researched lol, and no idea how to use anythin cept ball and sprinkler valves :P

Posted: Thu Apr 15, 2010 3:20 pm
by Gun Freak
Apparently you haven't researched... there is like a thousand threads on piston valves.

Posted: Thu Apr 15, 2010 3:23 pm
by Technician1002
Start in the Wiki. It has a section on piston valves.

http://www.spudfiles.com/spud_wiki/inde ... ston_valve

Posted: Thu Apr 15, 2010 4:22 pm
by Crna Legija
this should help