A friend of mine came across some 7.62 x 39 ammo marked 539/81 and 270/58 they are all copper washed. I've looked up the numbers and 539 is the Tula plant and 270 is a Ukrainian plant. Research I've done leads me to believe these are steel core. Can anyone weigh in with some info. Also possible value per round. He also has rounds marked 17/58, 17/k. The boxes are brown with a number 6 on them.

If they contain the original bullet they are indeed steel core.

But a large quantity of Russian surplus was recently released with a blunt nosed cheap Berry's copper plated swaged lead bullet in the steel core bullet's place to make it legal for civilian sales.

Cases were mfg in 1981 and 1958 for what its worth.  Without a picture, it's hard to tell if steel core or not, but I'd say they were based on the info provided.

Steel core, corrosive. Not AP. Some guys think they must have steel core and will pay a premium for it if you have cases or half-cases.