This is a discussion on Anyone using H4895 for 223 loads? within the Ammunition forums, part of the M14 M1A Forum category; With my 308 I pretty much fell into a great shooting load as 41.5 in LC brass was the first one I tried and it ...
With my 308 I pretty much fell into a great shooting load as 41.5 in LC brass was the first one I tried and it runs 100% but in 223 it has been less than cooperative. I am using RP brass, mag primers and 77 noslers @ 2.245" and have loaded from 22.7-23.5. It seems like there might be a load just below 22.7, and around 23.2, but it's hard to tell.
In a 223 there is no reason why any of the 4895 powders, that is IMR, AA2495, and H4895 will not produce outstanding accuracy. Lots of shooters have used IMR4895/H4895 in match loads with the 223 across all bullet weights.
I'm curious why you are using magnum primers. You shouldn't need them with 4895, and I wonder if that might not be your problem. I'd try a standard primer and work up again, see if that doesn't make the ammo settle down and behave.
In my Krieger barreled uppers 23gr over a 68, 75 or 80 Hornady shot much better than any other load. Significantly better. I had the same velocity of RE15 loads and I got my last points using H4895. Metered just fine out of a Dillon 550, just load and practice. Practice is what wins points.