ID Finnish 7.62x39mm unknowns

Any idea what these two Finnish 7.62x39mm are? Both are head stamped “SO 73”.

The one on the right looks like it has the projectile from a 7.35 Carcano. I know the Finns reworked Carcano brass, but did they reuse the projectiles also?

These are not mine, I only have this image and head stamp info from their owner. No info on weight or anything else at this time.

They were in a small collection of fairly common 7.62x39mm that I am helping someone identify.
Are the authentic or someone’s fantasy?