It is a great firearm, and I've never had any problems with my 602 or other Brno's. I have a photocopy of Chapter 27 "Czech Brno Sporting Rifles" from a book whose name I can not remember. I'll have time to trace it down next week. Jon R. Sundra wrote an article called "A Pair of Aces from CZ" which was published in both The Complete Rifleman #26 and Deer & Big Game Rifles Vol. 14 #1 2005. In it he compares the 602 to the new 550. The ZKK series ran from about 1965 to 1985. If anyone knows of newer ones please let me know, the date of manufacture will be stamped on the left hand side of the firearm.