Redrock,
These were made from about '34-'35 to '50's From memory.
Not serial numbered and several production changes . Including cocking, bolt configuration, sights , etc.
I have several of these old rifles and this is the oldest. I have forgotten most of what I thought I knew about the 69. I would guess this is from the 40's .

My interest in research has dwindled and I am off on other rifles.

I have been struck in the wallet by a rifle outta the Harvey Donaldson Collection. in the highly un-sought caliber.....- .219 Zipper in an old Remington Hepbern. To it's credit ...it sports an even more "Modern" optic in the flavor of Unertl.