The Czechs were forced, as part of the Warsaw Pact, to adopted the 7.62x25mm cartridge used by the Russians.
The Russian 7.62x25mm loading from the PPSh submachinegun was listed as 1640 fps from a 10.6 inch barrel and from the Tokarev pistol as 1378 fps. (With the Russians, their pistol came first and their SMG was adapted to the pistol round.)
In 1951 the Czechs adapted their Model 24 and Model 26 submachineguns (SMG) from 9mm to 7.62x25mm. However, they gave their M48 7.62x25mm cartridge a loading that gave them 1800 fps from an 11.2 inch SMG barrel. Then they adopted the CZ vz 52 (CZ52) in 1952 a year later to use the same ammo as their SMGs. The CZ52 pistol was listed as having a 1600 fps muzzle velocity with the Czech M48 load. (With the Czechs, their SMG came first and their pistol was adapted to the SMG round.)
(In WWII the Italians used three 9mm loadings for pistols and SMGs. All three cartridges were based on the 9x19mm Parabellum: a light 9mm Glisenti, a standard 9mm Parabellum pistol load, and a heavy M38 9mm for the Beretta Model 38 SMG. That is screwed up, but it is an example of "special" SMG loads.)
Velocity listings for Russian guns with Russian ammo and Czech guns with Czech ammo from W.H.B. Smith "Small Arms of the World", Stackpole, 1966.
The Model 52 pistol is a native design which has borrowed its locking mechanism from the German MG42 machine gun. The pistol is chambered for the Czechoslovak-made version of the Soviet 7.62mm Type P pistol cartridge, which the Czechoslovaks call the Model 48. The Soviet and Czechoslovak cartridges are interchangeable with the 7.63 Mauser, but are considerably hotter loadings than are the United States commercial loadings of this cartridge. For this reason, the functioning of Soviet and Czechoslovak weapons with commercially loaded 7.63mm cartridges is, at beast, minimal. The Czechoslovak cartridge has a particularly heavy loading, being about 20% heavier than the Soviet.
That is "heavier" in the sense of higher velocity than the Russian 7.62x25 fired from pistols or SMGs of similar barrel lengths. That is not necessarily "heavier" in the sense of chamber pressure, since you can get higher velocity with the same chamber pressure using a slower burning powder: anyone ever notice the muzzle flash of a CZ52 being fired with Czech 7.62x25mm ammo?
The CZ 52 pistol was designed to handle the recoil of the Czech M48 7.62x25mm load better than one would expect the Tokarev pistol to handle the recoil of the M48 round. It has nothing to do with claims of increased chamber pressure, but with claims of increased muzzle velocity, increased muzzle energy and (opposite and equal reaction) increased recoil velocity and energy.
Damage to 7.63 Mauser C96 pistols from 7.62x25mm ammo is not pressure: it is increased recoil impulse battering the bolt stop until the barrel extension cracks at the rear behind the bolt stop.