Well I can help...but not with BOC bottles. BOC are a pain in the **** if you want Argon instead of argoshield so I don't use them.
Air products X30 size for coogar5
Also air liquide O/A full size.
I'm going over fully to A/L as they let me swap and change the gas type and bottles I have with no charge. Also the local lorry driver will deliver for a drink if you don't want bottles next day. AP want yet more cash plus a £40 delivery charge.
Oxy acetylene
Argon is just that, pure argon, 'argoshield' is a a BOC brand name for a mixture of argon, carbon dioxide and oxygen.
For mig welding, agon mix is preferred though pure carbon dioxide also works and is also considerably cheaper but doesn't give as nice a weld appearance and is more spattery.