What's the difference? Is the 452 barrel threaded into the reciever? It looks like the 455 has set screws. No experience with either but am looking for another bolt .22 mag to replace my savage.
The older CZs have a fixed barrel threaded into the receiver and dual opposed locking lugs (the bolt handle and an opposing lug). 455s have slip-fit barrels secured by set screws and can be fitted with auxilliary barrels for other rimfire cartridges.
CZ snobs prefer the older ones. Others like the idea of having extra barrels. I had a 455, and decided that the switch-barrel process was too much trouble and would prefer dedicated platforms. The 455 does make using aftermarket barrels like Shilens very easy.
452s and 453s (set trigger) are getting scarcer and often command a premium. Some claim that they are more accurate; others say the 455s are just as good. After using my 453 in the woods for a couple of years, I decided that the bass-ackward safety, while no problem on the range, was a major PITA and bought a Ruger.
Here's a nice write up:
http://www.czfirearms.us/index.php?topic=32042.0I have 7 variations of 452/3s so I guess I'm a CZ snob. They all shoot very well with my .17HM2 Varmint shooting unbelievably well. With a YoDave trigger kit, they're as accurate if not more accurate than some of my Remington 541 and Anschutz rimfires.
The only production rimfire that I own that seems to be as accurate is a couple of Winchester 52Bs.