filling GBB with scuba tank???

[kidssg]

SO this is compressed air
Well I dont think it would work in a GAS Blow Back. and it if did (which I dont think it will) Youd probably have to apply silicone to the apilicator on each fill. I would stick with gasses made for airsoft if I was you.
The Kid

[Minky]

I could swear I posted this link before, but here you go: www.classicairsoft.net/Gas/gas.htm

It's geared more towards the classic airsoft guns, but there might be some useful information there.