I've had an "early" CZ452 Varmint and had a difficult time getting it to shoot well. I finally free-floated the barrel and bedded the action. That made all the difference, but it wasn't the rifle for me.
A a year or so ago, I bought a new/used CZ455, .22WMR and it had problems that I corrected, including bedding, firing pin shape, and trigger pull. It now shoots MOA at 100 yards with the right ammo, but with other ammos varies from 1 1/4 to 3 MOA. I was immediately attracted to the woodgrain of this rifle and apparent newness in the used gun rack. It's lightness and accuracy make it my favorite walk-about rifle.
The 455 is a switch-barrel design, but because I never intend to shoot either .17 HMR or .22LR in it, I LockTite-d the barrel in with Steeve and Bearing Mount. It worked for my Ruger 10-22, and seems to have helped the 455.