Just got done going through this last night with a 30 yr old 22" rem adl that they called their mountain rifle that has a pencil thin barrel. This rifle doesn't have maybe 300 rounds through it and has been pretty much playing safe queen. Started 2 weeks ago, had quite a bit of IMR 4350 and no H4350. So I used the IMR4350.
After loading 2 sets of ladder tests that were the same I ran them through my magnetospeed at 400 yds, then I loaded up 2 groups of three and ran for group accuracy at 200 yds. with charge that showed potential from the 2 ladder tests. One group was 1.1 MOA (had a flyer or a driver malfunction) and one was .4 MOA.
This was using berger 168 classic hunters, lit with fed 210M primers.
Next thing is to stretch it out to at least 700 yds and we'll see what I can do with that pencil thin barrel at distances. Can't expect too much from a 8 lb fully dressed setup.
I just wish I had had some H4350 and was this far along - but that's just because of personal preference.
I ended up having to push them pretty hard to get much velocity but am not showing any pressure signs at 70 degrees outside temp at 3500 ft elevation.
4350 will pretty much fill up an '06 case to get any velocity out of it.