The photo below shows a couple of South Ossetia militia. The guy on the right is carrying a Sako TRG.
It is unlikely Finland would allow arms exports to South Ossetia. It was probably bought on the civilian market and then exported. I cannot imagine that South Ossetia would have many snipers so this is feasible.
Their squad sharpshooters (or whatever they call them in that part of the world) are probably using the SVD.
I cannot make out if it is a TRG-21 / 22 (.308 Win) or TRG-41 / 42 (.338 Lapua or .300 Win Magnum). I have never seen a photo of a 41/42 without a muzzle break, but I think the 21/22 can have the Sako TRG muzzle break attached, please correct me if I am wrong.