In a couple of .260s, a 6.5 Creed, and a 6.5x47 Lapua... I've seen virtually no difference between IMR4350 and H4350. Identical loads shot essentially identically in terms of accuracy, velocity, POA/POI, and temp sensitivity. I've shot 24 pounds of H4350 and about 10 lbs of IMR4350 in the past 4 years out of the above rifles, mostly with 123s but some 139/140s have been mixed in... and I shoot the exact same charge of each powder and very little changes.
I haven't seen velocity vary between the two powders more than about 30 fps...
I have't seen POI vary by more than about 1/2"...
I haven't seen accuracy degrade/improve by more than about 1/4" or so...
I haven't had any POA/POI issues in temps between 0-90 degrees...
I'm sure some guys can quantify the huge difference between the two powders... but I certainly can't. That's only over the course of about 5000 rounds of mid-size 6.5s though....
