IMR 4227 vs. H4227

[jg7]

[mark501w]

Imr&H series powders are not the same

[gunboat]

They are close enough for all but max loads --
For cases like the hornet and bee you can't get enough in the case to matter. --

[Cheap Shot]

not the same

re-work your loads. The H powders are said to be more temperature stable, they lump them in with varget.