Fairly standard load to test barrel ability is LC or WW brass, 25.0 Varget, CCI BR4 and 69 sierra match king at 2.250 OAL.
What kind of velocity do you get from that load?
Can't recall, its been about 96 or so since we quit shooting Varget in the 223, but that load was pretty much a blind given if you needed something to run with and no time to test etc.. in the AR.