An old octagon barreled mod. 94 Win. in 25-35 calibre recently came into my possession.
Unusual in that it has no serial number, and no, it has not been ground off. The front end of the receiver measures the same as three other mod. 94s in my gun room.

can anyone enlighten me on this unusual situation?

All that I have seen have been blessed with a serial number. Yours may have been a "lunchbox special"; smuggled out of the factory a piece at a time and assembled at home.
Probably considered a perk for working at the local gun factory.