Re: Winchester 52 Bluing
^^^ Correct.
That said, you won't do any more harm to the gun than has already been done using a bit of cold-blue on a q-tip. Damage is done. Polishing it and re-bluing (without exactly matching the Winchester finish) will cause far more harm.
A bit of cold blue touching in the visible spot will at least make it go away... the gun is fully usable... and it won't have hurt the other finish or the stampings/markings, etc.
There are 52 restoration specialists as RTH says. They are expensive. Unless you really want to dump double into the gun than it's worth... touch it up as best you can, move on and enjoy a suberbly accurate rifle. Mine is a one-holer on a small bore range. I used to call it my 'money gun' because I won so many 50-50 shoots with it up at the old Edwards firing range outside Cols. Oh.
Of note, An interesting fact of rust bluing and case hardening is that environmental conditions of the area where it is done affect the outcome. When the Chas. Parker company moved from Meriden, Ct. to Ilion NY with the Remington purchase, the case hardening was never the same. Larry DelGrego Sr., the late master Parker Restorer, could never quite get it to match because of the different humidity, salinity, etc. Interesting... I would have thought that there was not enough difference, but he always claimed that the same equipment running the same processes by many of the same people was just never the same at Remington. And this was with bone, not Cynide, coloring.
So there may be other factors in the process than just re-rust bluing. Restoration is a slippery slope on some guns.
OP... please post some pictures. I love to see 52's!
Cheers,
Sirhr