H4895 isn't a good match for either of your applications. You will run out of case capacity before obtaining decent 223 performance, and low load density and high pressure in the 6.5 before getting a decent velocity. It could be OK with heavy 223, or very light 6.5mm bullets though.
You will be able to make ammo that goes bang and could very well be accurate, as I'm sure someone will attest to shortly, but velocities will be lower than desirable.