Need help to ID some 7.62x25 ammo.

[MVP]

Comparing this two cartridges.

For 38-77
The core of the projectile was very hard to scratch with a screw driver and attracted by a magnet so I assumed it is steel core.

For 3-46
Core was separated from the jacket when I cut it open with a angle grinder. The core was soft, easily scratched and marked and did not attracted by a magnet. The jacket did attracted by a magnet so I assumed it is copper washed lead core with steel jacket.

The steel core projectile (38-77) is longer than the lead core projectile (3-46). (Someone mentioned this in another forum)

The powder in (3-46) is more than the powder in (38-77), Maybe (3-46) runs hotter?

First three images are the cut opened projectile from (3-46). The 5th image is the cross section of (38-77)