When I was there a couple of years ago all the honor guard types (Palace Guard, City Guard, couple others with different uniforms I couldn't figure out what they were attached to... they seemed to be really into honor guards as a tourist attraction)... Were all carrying VZ 52 rifles of some flavour.
When I get home tonight I'll see if I can dig up a pic.
Fun fact: the Czech Government hired the costume designer from the film "Amadeus" to design the uniforms for the "Palace Guard" - which hadn't existed in almost a century - as part of their conscious efforts to draw western tourists (and their cash) as part of thrir economic revitalization after the fall of the East Bloc.
Most of the various honor guards you spot in different parts of Prague stem from that time.