Imr 4831 was my grandfather's and my my dad's go to in a 270win with a 150gr Sierra gameking for years. Still use it in my dad's.
I've used it with with a 208 amax in my 300winmag. Not posting that data though. It was over 3000fps out of a 26" shilen. Cool weather only lol.
Never heard of it used in a 243win, but I have 243AI that I may give it a shot in. It loves the 85gr sierra hpbt gameking. I usually use imr4064 in the 308 based cases.
And in a 223? I'm going to have to try this one. It should favor the heavier bullets right ? I'm kind of glad this thread was resurrected.