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.