Hi, I think all the red shellac was added with post war refurb. I have 2 PUs that were not refurbed, from Samco, and they both have a brown oil looking finish a lot like linsead oil. I also have a 91/30, not refurbed, with the same brown oil(not shinny or slick) finish.
Ted will know for sure. It is probably somewhere on his site.
From Left to Right
1 and 2-- Finn stocked/captured, but Century put togethers, No Shellac
4,5 and 6-- Post war refurbs, all with Shellac
7-- Hungarian M-52 with probable Viet Nam applied mud varnish
8 and 9-- Samco, not refurbed, brown oil like finish(made more shinny with Howard's)
10 and 1-- ex-PUs, post war refurbs, with Shellac.