Should take about the same, give or take, as the other 75-80gr .224 bullets designed for single feed slowfire events: ~24.5gr RE15 or Varget, don't recall what H4895 charges were, 23-ish gr or so. Start lower and work up. Otherwise, go search thru the Florida HighPower forums; should be a variety of load data for most of the heavy .224 cal bullets over there:
forums.delphiforums.com/flahighpower/messages
HTH,
Monte