I post this response in the interests of information requested by the OP, and in partial response to some of the replies above.
I'm not going to be so dogmatic to suggest that ALL CZ 550's require an action job before they funstion, because that's simply not true.
I also do not intend, nor wish to, start a Cz bashing thread. Those we have already seen and most would be well aware of issues raised in the past.
I currently have a Cz 550 being worked on by a gun-smith in order to resolve the firearm's inability to feed reliably.
The gun-smith I took this rifle to acknowledged he had worked on "numbers" of Cz's with the very same issue.
The gun-shop I recently purchased components for other firearms from has a young fella working behind the counter I regularily deal with who also acknowledged he is almost at the end of his teather in trying to get his CZ 550 in 458 Win mag to feed reliably.
A good freind of mine, who also operates buffalo hunts in Australia, has been through two different CZ 550's, one in 416 the other a Custom Shop 404 which he waited 2 years to be delivered then as he was picking it up he insisted on cycling live rounds through the action before picking it up and paying for it (was taken to an acceptable area by gunshop staff to facilitate this process) and the BRAND NEW CUSTOM SHOP RIFLE DID NOT GET THROUGH THE FIRST CYCLE. NOR THE SECOND, NOR THE THIRD ETC ETC. Needless to say my buddy did not pick this rifle up.
I followed up through a complaint on his behalf to the importer of Cz's into Aus who acknowledged these issues were far from rare.
My buddies second Cz, a 416, cracked the pistol grip woodstock before it's 200th round.
My neighbour, who operates hunts to the North of me has at least a couple of Cz safe queens that no longer get used as they will not feed reliably and he does not have the lack of consciounce to sell them to anyone.
I personally have another Cz 550 in 375 that feeds and functions perfectly, as do several others that I know about.
I'm not for one minute saying that all Cz's are crap, they're not.
But they are a mass produced firearm put together with parts manufactured in a country with unknown quality control procedures, built to meet a low price point.
You get what you pay for, mostly good, sometimes shockingly poor.
Obviously "lemons" are apt in every brand, that I also ackowledge.
Being aware of these issues may at least help you select the right individual firearm.
Insist on being able to cycle live rounds through the action of the individual rifle you may have selected, and do it (in a place that is safe to do so) and as quickly as you possilby can.
No hate mail thanks, these views are my own personal experiences and opinions, none of which may agree with or reflect your own.
Good hunting to all.