Hey Max, I think this is what you need:

http://www.ebay.com/itm/CO2-Tank-22m...item3f1cc537ae

The male part which mates to your co2 nut is DIN477-6 (0.860")
The female part is CGA320, which is interchangeable to 1/2"Bsp, add a 1/2" angle if you need it that way... hope this helps