I load with benchmark 25.7gr, winchester primers, uniformed flash holes and the 50gr varmint grenades, works for the 52 gr Berger too.
Looks like you could stretch out the OAL, make as long as possible that will still fit in magazine. Mine likes the bullet to start close to the lands, just touching if possible. Sometimes I'm a bit lazy and don't make them as long as I should. Check with a marker if you are touching the lands.
A buddy shoots a HB tikka 223 using varget with good success. I've chose not to use it as the difference between min and max load was fairly tight and didn't allow for much metering error. The spread for benchmark is greater therefore metering error has less influence on performance.
Forgot- I shoot the cz also, action is smooth like silk. Sound like there is something wonky with yours.