The 323 headstamp round is Romanian, could be corrosive or not. I'd guess it is.
539 is Russian Tula. I expect its standard corrosive M43.
I "think" the far left round is an "S", and Sako/Laupa made non-corrosive brass case. The font looks right to me. If so, it COULD be boxer primed and reloadable, though I think they switched a little later than 78. In any case, that's likely very accurate ammo compared to the others. So maybe save that for special occasions or whatever, and definitely check the empties. It was pretty highly regarded about 10 years ago when a bunch of it got on the US market. A few people were butt hurt that it wasn't as accurate as commerical Lapua, but it was still better than Russian in my experience. At the time, I preferred buying Yugo M67 though.
ETA: OP, can you take a magnet to them? I'm really curious if the far left is brass, and whether it has a magnetic bullet.