Military Mauser action, looks like a 98 action, though it may be a 95, I'm no expert. Military action, for sure, the thumb slot identifies it as that.
The barrel is "odd", meaning not typical. Generally military Mausers have a stepped barrel, and the front sight on that barrel, ALONG with the barrel date and what could be the Ordnance mark (flaming bomb?) put me in mind of a 1903 Springfield barrel.
So, as a wild guess, I think what you've got is a Mauser 98 action, "scrubbed" meaning most markings removed, rebarreled with a WWII Springfield barrel (8-44 date), as a project for someone, and later abandoned.
The entire bolt assembly is missing as are the bolt stop pieces, action screws, and stock. if it is a Springfield barrel, then the bore will be .30, but the chamber could be anything from what's left of the original .30-06 chamber to a custom cut chamber depending on where the builder stopped in the process.
All the needed parts are available, though fitting a new (replacement) bolt and finish chambering /rechambering the barrel and headspacing are jobs for a qualified professional gunsmith.
Returning the rifle to a usable condition will not be cheap, nor will it be cost effective. It will cost more in parts & labor than the rifle will ever be worth.
As a project, go for it, if you have the funds. You could spend thousands of dollars to make it a high grade custom Mauser that looks great, that will only bring $450 (if that) on a gun show table...
Good Luck!