I have never heard of a .223 that can compete with run of the mill .222's. I do not know why,
except that perhaps most .223 shooters are not BR shooters, or - because the .223 is not being
used in BR contests, yet there are still some hold-outs shooting triple deuces.

Food for thought, though. I know there are guys with specially build AR's who are shooting sub 1/2"
at 100 yards with a variety of ctgs. from .223 to .17 Rem to .204 Rugers, but I have not heard of
.223's that can compete with varmint weight .222's that routinely shoot 1/4" and smaller at 100yards.
Mine still does.

Now, due to it's military use, it is possible the hunting and varmint type rifles chambered in .223 have
military-shaped chambers. What that means is likely attention to throats and lead angles that will increase
barrel life and possibly THOSE differences do not translate into tack-driving accuracy?
So, I don't know.