I have refinished my fair share of milsurp rifles that need some love.
If I am keeping them period correct then it linseed oil and tung oil.
These old finishes are a PIA to work with but are period correct and for that type of restoration the correct products to use.
With that said I have a few that are way past the collector value.
Some even saw some BUBBA handily work. (not by me)
I call these shooters.
These I refinish with modern finishes.
Much faster, easier and convenient.