From looking at your bottle I would solder a 1/8" brass close nipple to a spent cartridge in the end, add a hole in the cartridge retaining cap for the nipple to stick thru. Add a corney gas in fitting to this nipple then to your regulated C02 system. The problem I see is the 1/8" NPT vs your ball lock thread. There's a will there's a way.
Bier Jagdwaffe... Bier 30 zeit.....~~=o&o>..........