I shoot 88s in a repeater in 223 with a 26” proof carbon barrel and get 2840 fps using h4895. 23.5 grains I believe is the load. I use MDT mags which allow to be seated further out than AI mags.
Having said all that, I think the 85.5 Berger is the best 223 bullet for a bolt gun. But the 88 is...