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Bolt Action Rifle run on Propane

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Bolt Action Rifle run on Propane

Unread postAuthor: spudnutbutthut » Wed Apr 14, 2010 6:57 pm

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?
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Re: Bolt Action Rifle run on Propane

Unread postAuthor: jackssmirkingrevenge » Wed Apr 14, 2010 7:21 pm

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.
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Unread postAuthor: iknowmy3tables » Wed Apr 14, 2010 7:27 pm

why is it called a CO2 bazooka if it runs on propane?
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Unread postAuthor: spudnutbutthut » Wed Apr 14, 2010 8:13 pm

LOL!, i dunno why i put Co2 in there. Could you maybe post an example of what jack described?
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Unread postAuthor: clemsonguy1125 » Wed Apr 14, 2010 8:44 pm

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Unread postAuthor: spudnutbutthut » Wed Apr 14, 2010 10:38 pm

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?
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Unread postAuthor: jackssmirkingrevenge » Thu Apr 15, 2010 12:06 am

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 ;)
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Unread postAuthor: spudnutbutthut » Thu Apr 15, 2010 2:48 pm

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
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Unread postAuthor: Gun Freak » Thu Apr 15, 2010 3:20 pm

Apparently you haven't researched... there is like a thousand threads on piston valves.
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Unread postAuthor: Technician1002 » Thu Apr 15, 2010 3:23 pm

Start in the Wiki. It has a section on piston valves.

http://www.spudfiles.com/spud_wiki/inde ... ston_valve
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Unread postAuthor: Crna Legija » Thu Apr 15, 2010 4:22 pm

this should help
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