I have actually shot, and still have some of that exact year, factory, and lot headstamp of bulgarian 7.62x25 that i shot some of though my CZ-52, never busted it open, but it did crush one of the two rollers while shooting S&B after having shot a rather large ammount of hotties. I dont know about CUP or the max pressure, but some handloads with H-110 that i made with the same pulled projectiles shot faster. (1770fps with an 86 grainer)
At this time i dont have the money, the reloading data that i lost to my laptop crashing, or the time to get to the bottom of this, but rest assured this is something i care enough about to actually figure out, and if the CZ-52 is a stronger action i then a romanian TT-33 ill find out, even if it requires blowing one up by accident in the process. The fact is that my CZ52 in otherwise exelent condition, with a Wolff 18.5 LB recoil spring crushed one of its rollers, and with factory S&B ammo. I admit i had hot-rodded it a bit before that, but it had been stripped and cleaned before the few hundred factory rounds ended up flattening the left locking roller, and it wasn't even starting to peen out or anything. It was destroying itself with the 18.5 LB spring and S&B ammo, i ended up putting a wolff 14.5 (factory strength) recol spring back in and replacing the rollers and shooting it a whole lot more with both factory, handloads, and the "super-hot oh so dangerous bad-bulgarian" as mentioned on that site, and it held up fine with the weaker spring untill i ended up getting rid of it in a trade. Bottom line, with the higher power (18.5 LB) spring, the locking piece and rollers were taking an obvious beating that they could not sustain. That boosted my muzzle velocity about 75-100 FPS, but was destoroying the action in the process. Peening out the locking piece and all.
I have not taken the time to put a TT-33 though such paces, but i will end up doing it within the near future. I know what achieved muzzle velocitys and loads were stressing my CZ-52 to the point of it not being able to cope, and will find out pretty soon weather or not the TT can take it or not.
All i was pointing out were the fact that i have heard of quite a few busted CZ-52's and never one TT-33.