Just for a little background. My father who passed away had a sporting goods store in Gary Indiana, my dad mentioned several times over the years that he bought a few different grade stocks, actions and custom barrels, then fitted the set together and sold most but kept this one.
I think your explaination is here.
Those receivers could be purchased as a receiver.
Ordinarily,the manufacturer,model,caliber,etc would be marked on the barrel,left side out ahead of where a scope objective might be.
The caliber marking would be obvious without removing the stock.
Of course,I don't know the story, But your Dad may have fitted,or had a smith fit,smething like a Douglas barrel. Most all take off barrels will be roll stamped .Nearly every sporting goods store that sold guns had a smith on staff or at least had one who did their work.
Or,maybe FN (or?) sold blank,unmarked barreled actions,to be marked later to suit the reseller,be it Browning or Ted Williams or JC Higgins.
They are all the same pattern,so a Mark !0 or Parker-Hale stock could be fitted easily.
Lets not forget Shotgun News and Gunlist had "deals" including Springfield sporters,SARCO, J=G Sales,Numrich,etc. where production leftovers were marketed. You could buy three or six of those stocks or receivers or barrels.
I'd say your Dad put that rifle together from a receiver,barrel,and a stock.
He picked good stuff. Buehler mounts were top of line.I'm curious about the scope. It looks a lot like a Lyman, but its a bit different from my All American.
You have a fine hunting rifle there. Your Dad had his hand in it,it seems.
And the 30-06 is a proper cartridge for just about anything.