mod a GBB airsoft gun

[wyz2285]

hi everyone
I´m planing buy a gas blow back airsoft mp5, and I found out that the magazine also serves as the gas chamber. So I thought is it possible to connect a paintball air source to it (with regulated pressure as the operation pressure of the gun) instead of using propane?

[jackssmirkingrevenge]

[wyz2285]

so it works !! thx Jack!
but should I keep using the same pressure as the "green gas" used originally or I can go a little bit higher?

[jackssmirkingrevenge]

but should I keep using the same pressure as the "green gas" used originally or I can go a little bit higher?

I wouldn't go too high, remember that in a hammer valved gun more pressure doesn't necessarily mean more power as it increases the force trying to keep the valve shut.

Also you will be going beyond the design limit of the blowback mechanism, so a marginal system is more likely to break.

In short, unless you plan on upgrading stuff like hammer springs, bolt springs etc. I would keep it "standard".

[wyz2285]

hum... so I will have to open the gun, test it and see if I have to mod some internal partes .If I keep it standard, will the power decease? as air does not behave as propane.

[Gun Freak]

Air expands faster than propane, so I think you'd get better velocity... Not sure though...
This would be a sick project...
Polar Star kinda beat you to it though haha.

[jhalek90]

You keep using "green gas" and "propane" interchangeably, is green gas propane?

[jackssmirkingrevenge]

You keep using "green gas" and "propane" interchangeably, is green gas propane?

http://www.airsoft-innovations.com/green-gas-propane

[Mr.Tallahassee]

I believe the pressure of propane at room temperature is somewhere close to 110 psi or ~7.5 bar. A HPA tank would give crazy numbers of shots if regulated that low. I agree with jsr, I wouldn't risk over pressuring because the gun could go pop (in a bad way) and even if it didn't the performance would suffer without extensive modding.

[Lazyboy]

Tapping the mag is a common way of fitting an external rig to an airsoft gun

[wyz2285]

Air expands faster than propane, so I think you'd get better velocity

I thought this too, and as propane expands and cools down (from liquid to gas) , I should get better accuracy too
this project is going to kick ass

[wyz2285]

just another question: if I put a tyre valve on a GBB pistol´s gas chamber(also serves magazine), can I use air instead of propane too? it would be cool if I don´t need to buy gas for my guns any more

[cammyd32]

just another question: if I put a tyre valve on a GBB pistol´s gas chamber(also serves magazine), can I use air instead of propane too? it would be cool if I don´t need to buy gas for my guns any more

ermm possibly. You would need a bigger secondary chamber though to go with it, the gbb guns mag won't be able to hold much air for repetitive firing.

[wyz2285]

but with propane one charge can do at least 30 shots I think, more than enough to finish one magazine of bbs

[warhead052]

Try it. But I would buy another mag so that if it fails, then you can still use it. What sort of pressure would you put into it?