Central Europe has been the stage for major wars for centuries. Good portions of the Thirty Years War occurred in Bohemia, which is the old name for Czechoslovakia, which is the old name for the Czech Republic.
In other words, the people there have a long history of fighting.
CZ guns have been around for a long time.
Also, if not for the Soviet invasion, who knows how advanced the Czechs might be? Prague has been a major cultural and arts center for a long time (again, counting in centuries).
It's not like CZs come from some backwater.