My first .CZ had a .223" muzzle, but just ahead of the chamber, the groove dia. was .224".
It shot the .223", 45gr. Hornady SP's about the same as the .224", 45gr. Hornady SP's.
What it really liked was the 40gr. Barnes and Sierra, athough the sierra 40's would be too tough for the 3,300fps I was getting.
My first Lux CZ -
My second Lux. CZ