As you've already discovered, it's been repolished and blued.
1930 production,,the receiver should be Carbonia Blue (Machine Blue) and the bbl rust blue.
You're correct in that the type of receiver blue flakes and wears off much more easily than the bbl blue. Leaving many otherwise pristine rifles with receivers showing less than perfect bluing coverage.
The polishing directions are correct (rotational,,not lengthwise) except for one missing.
On the sides of the leveractions, the rebate scallop cut at the rear of the side is not parallel to the rebate cut at the front.
That makes the polisher take an extra cut or sweep at the rear rebate to polish that area at a slight angle to the rest of the side.
The slight variance in width of that angled polish cut is more easily seen on some than others,,probably just a result of who rather than how it was done.
It shows wider if done after the side was parallel polished,,very narrow if done first. But in every case it's still present.
It's all done on belts and hard wheels. No hand polishing afterwards. Straight even polishing grit lines.
Nothing of the back and forth scratch pattern seen from hand polishing.
The sharp edges of machine polishing are missing here. The best of careful hand polishing will dull the edges.
Those crisp sharp lines on early firearms like Colt & S&W were put there with polishing belts and wheels.
It takes alot of skill to do that holding the part in your hands against a wheel.
The polishers in the old factorys were amoung the highest if not the highest paid skilled workers
I can't see it in the pics, but the serial number stampings should be standing proud and sharp as they were done after the polishing was done.
The proof mark on the recv'r looks slightly different in oval shape fom the bbl mark. Can't see the W/P markings inside the oval to compare.
They both should obviously be the same and done through the blue.
They were applied to a finished & blued firearm,,and should show it.
Aftermarked Winchester and other proof and mfg'r marking stamps are available for restoration work.
They aren't always represented as such however.
