Despite having found a reasonable(ish) price for these disposable bottles - Fat Bob's Paintball Emporium - I'm a Yorkshireman and I still think that I can do it cheaper

Background: I'm working on a project to convert a Daisy 990 switchable CO2/pump rifle from 12 gram bulblets to a larger refillable CO2 source. The airsource bottle will just fit into the stock, after some slight mods, and I can get a hose and bulblet adaptor from Cooper-T. So far so good.

But ......
What I would like to know is; does anyone know of an adaptor that will enable me to refill these bottles?
Am I tight, or am I tight