A nice serviceable stockman with virtually indestructible Delrin handles.
However, it was made after Robeson went out of business in 1965, probably by Camillus, possibly by Ontario Knife.
The pattern number on the mark side of the master is the tell on that.
Still, at flea market prices, probably a good grab.
You did a great job cleaning it up.
I think I might have a pic of one here somewhere. Actually, I may still have this new old stock knife.
For whatever reason, mine looks to be a bit more slim than yours.
And yes, the pattern number explains the knife.
The first digit describes the handle material. "6" was originally for bone, but was used during and shortly after WWII on some jigged black composition handled knives and was kept after they transitioned from bone to Delrin.
The second digit described the number of blades, so "3".
The third digit described the bolster/liner composition and "3" was an indication for nickel-silver bolsters and brass liners.
The last three digits were the handle-die shape number. "884" was a 3 5/8" serpentine stockman pattern with a "Turkish" clip master blade.
Charlie Noyes