its recommended that you get a new regulator as the pressure in Argon cylinders is higher than CO2 cylinders (as has been indicated by the knowledgable people on here) but machinemart sell the adaptors part no 010120115. but if you only have a single gauge regulator, you wont know how much gas is left in the argon mix cylinder
I used mine on a 137 bar argon cylinder with a machine mart adaptor and then later got a new regulator