Here's a little ammo comparison I did tonight. Please keep in mind, I'm, at best, a mediocre deliberate shooter.
Shot 3 flavours of surplus 7.62x39. The regular Czech Tbpl/Fe, Chinese copper-washed, and the Czech Fe/Fe (the grey on grey stuff). The steel on steel on steel Fe/Fe is fairly uncommon, I've only come across one case of it.
I shot my XCR off bags on the bench. 10x40 Bushnell mil/mil scope. XCR pistol mags.
Target shot at 100m. Groups were shot from top left to top right, and bottom left to bottom right. One flyer in the first group and the last group only had 7 as I used up a few more than I planned sighting in. All groups were shot at gas setting 2. The Fe/Fe and Chinese will run perfectly on 1 but the Tbpl/Fe requires 2 for consistent operation. I was interested to note that the Chinese shot to a higher POA than either Czech type.
All groups were 10 shot, except the last, fired fairly rapidly and all the shots in the group came out of a single magazine.
Using my scientific tape measure here's the results. What do they show? IMO, with me behind the gun using the surplus I have on hand it's pretty much a 3 MOA combo with the groups just over 3" at 100m. I'm not sure what happened with the second Chinese group but no doubt it was me. I'm also sure a better shooter will get a better result.
I've got some Wolf HP and some Sako surplus that I'll shoot for group next time out.