Czechoslovakia adopted the 7.62x45mm cartridge after World War Two, introducing both a vz.52 rifle and vz.52 light machine gun using the round. It was about 200 fps faster than the Soviet standard 7.62x39mm. It was marginally more effective in the LMG, but not so much that the Czechs put up a big fight to keep it, and changed over to the 39mm round in 1957. At that time, they converted both the rifles and light machine guns to the new round with the designation vz. 52/57. The rifle would be quickly replaced by the much superior vz.58, but the LMG would stick around for a while.
The vz.52/57 machine gun is the last production iteration of Holek’s original ZB 26 light machine gun. This design was tremendously successful, with the ZB 26 and slightly improved ZB 30 doped by many nations. It was also the basis for the .303 British conversion that became the Bren. Scaled down to intermediate cartridges, it was used by the Czechs in this form and also copied by the Finns as the KvKK-62.
The vz.52/57 is one a rather small group of guns which can be fed from either belts (50 round here) or box magazines (25 rounds). It is also one of a small group which use the pistol grip as the charging handle. Despite not seeing more widespread us, it is mechanically a very interesting and claver design.
Thanks to the Institute of Military Technology for giving me the opportunity to bring this 52/57 on camera for you!