Navy Commercial Help

[MAUSER88]

How can I tell if this is a 1906, 1908 or 1920 Navy Commercial? Serial number is 7682. Crown N under barrel. GERMANY stamped on left side below another a Crown N proof. DWM 1915 dated. Correct concentric circled wood bottom mag. that is unmarked.

Looks like three Crown proofs with an S maybe under each one and one Eagle with wings up.

Is the shoulder board legit too? What do the stampings mean?

Any ID would be most helpful!! Please check out the pics.

Any idea of the value would help too. It's all matching and the bore is exc+++