Even H4350 was almost unobtainable for a while, and I used it for more handloads in my rifles than any other powder.
But about the time my stash of H4350 started to get low, IMR4451 appeared. While it is made in Canada, unlike H4350 (or the Belgian Ramshot powders), it doesn't have to shipped across an ocean.
I tested 4451 and found it to work just as well as H4350, so switched over. So far "working up" loads has been very easy: I try a grain less 4451 than H4350, and the result either spot-on or very close.
Ditto with 7977 vs H1000.I was in the same boat as you. they are pretty much interchangeable.Been pleased with the Enduron IMR
