Help on what this gun is?

[worktruck61]

Purchased this gun from a local online auction where they called it a Rolling Block (16 gauge?). I can say that 16 gauge shells do not fit in the gun. It has a round barrel that is 30 1/2" long overall gun length is 48". The inlay is flush and I'll assume was not factory. But help on whom might have done it, how to find what year it was manufactured or other general information would be appreciated.