Hello AUTiger73. I have a CZ527 in .223 Remington. Even with its light sporter bbl, I've never had any problem getting the gun to "shoot." With favored handloaded, I can get 3 shots into about .6" @ 100 yards on a still day and with Federal 55 gr BallisticTips, about .75". The best load I've found for it is a factory load: Winchester (Combined Technology) 50 gr BallisticSilvertip. It regularly drops these into about 3/8" @ 100 yards.
I have no idea how the 527 will do with regard to the 7.62X39mm. I suspect it'll do OK, but I'd go with factory commercial ammo as I suspect it'll be a bit more uniform than some (most?) of the surplus stuff. Also, my 527 occassionally fails to pop the harder military primers, but never fails on any other be it factory or reload from Winchester, Federal, or Remington or Hornady.
These are quality little guns in my experience. I own two other CZ/BRNO rifles. One's in .30-06 and the other in .375 H&H. They, like the 527, are reliable and accurate.