Still haven't gotten an email back from Hodgdon and still haven't had a chance to call them. I did however email ADI about their AR2205 powder, which, according the link provided by mehavey, is/was H4227. This was my email:
"Is IMR 4227 that is now imported from Australia by Hodgdon Powder Company the same powder as your AR2205? Was AR2205 previously imported and marketed in the USA as Hodgdon H4227? Inquiring minds want to know..."
This was their response:
"Thank you for your enquiry from the 30th May with regard to reloading using ADI Sporting powders. ADI AR2205 is supplied to our partner Hodgdon Powder Company for distribution in the USA. This is the same product that is supplied to the Australian reloaders market.
We have been supplying Hodgdon with AR2205 for many years and plan to do so for years to come.
Refer to our website at www.adi-powders.com.au
or our 5th edition handloaders’ guide for more information, warnings and reloading safety.
We thank you for using ADI Sporting Powders.
ADI Technical Centre"
Not exactly coming right out and saying it directly but I think it is safe to infer that the Australian imported IMR 4227 is H4227.