I put 10 rounds of S&B (Czech) over my chronograph last February.
High vel ; 2416 fps
Low vel: 2353 fps
extreme spread: 63 fps
Average vel: 2383 fps
I also did Russian surplus & Chinese surplus ammo the same day.
Russian was 2354 fps
Chinese was 2345 fps
Chinese had smallest extreme spread (40 fps) and gave best accuracy @ 100 m. (2.5" group with SKS with Bushnell TRS25 red-dot sight)