Checked wikpedia, the article doesnt mention actual year the CZ550 was produced. I got one in 416rigby at the end of 1999... I think. I remember them being quite new then, a replacement to the Brno602. Anyone got an exact date any calibre in CZ550 hit the market?

No exact date, you must be close with 1999.
The first CZ-USA catalog/brochure I have has no date on it but they were bragging about their 1999 IPSC team silver medal.
I bought my first CZ 550 Magnum .375 H&H in 2000 in KY.
I also found an action-only at Great Northern Guns in Anchorage, AK in year 2000, with serial number AHR 50001.
I always wondered if someone had liberated one from a special batch serial numbering for AHR.
Sleuth it out for us, Karl.

Sorry for late reply, will do my best Ron. Back on the move again remote sites, so can only get to services intermittently. I have emailed CZ themselves and see what they say.