I'm with thef other guys here .. can markings are 7.62x39. They come in 440 per can. on your next run out you want 750 or 660 rounds per can. Mosin for your bolt, or SVT for your semi. Either klick like a canon on a stick
Type 53. Is for the Type 53 Mosin Carbine.
Different powder burn rate?
You wilted Flower...it's stiff, but not too bad, and I shoot a 6mm because my shoulder is unhappy with anything heavier than about 100-110gr projectile. As for the rest, kind of confused, 7.62X54R is used buy the Mosin Nagant, and the SVT, and I could be mistaken but the Cartridge in question is on the left, 7.62X54R by the look of it.
Why don't you take it back. They told you it was one thing, and it wasn't. Store policy on no ammo returns shouldn't apply if the staff can't properly ID what they sold you.