I think I'd go with H380 with that said, I have Weatherby .224 Wby Mag, with a 1-14" twist... it's one of the older Wby MkV miniature action 26" barrel. Actually, I have two of them the other one was in a 22-250 Rem which I had re-barreled to a 6XC Tubbs, but I digress. My 1-14" twist will shoot nothing above 50gr bullets with any accuracy, that is, if I go to 52-53 the groups start coming apart'..., go to 55 and above and it's a shotgun... The Barnes 50gr'ers I use are the older 50gr "VLC" blue coated bullet {22491} **** shame they're not making the "blues" anymore, they make the same bullet but without the coating, however... I like the coated and I bought a lifetime supply when I had the chance so I'm good. So, my point; I think I'd stay with the 50gr and lower weight bullets in your 1-14" twist rifle no matter what powder you choose.
Top 6XC
Botom Wby Mk .224 Wby Mag
are tac drivers.
Top 6XC
Botom Wby Mk .224 Wby Mag