I hope the 'heavies' work out for you, that is what the Hornet has needed for a long time (IMHO). Because mine wouldnt work with them I went to the 25-20 and 25-35 (I wanted to play with them anyway), but a downloaded 223 probably would have worked too.
Good luck, it is a neat, economical, relatively quiet cartridge, just go slow & easy in reloading, the cases are thin. BTW, I really liked the Lee Collet Sizing Die for mine, it saved a lot of time & mess (case lube, etc).