blueing

i did read the message of the byf 41 and its blueing. now i have some questions about my k-dated S/42-mauser from 1934:

the grip and the barrel are 100% in original-blueing with some places without any blueing, because it was weared in a holster. the inside of the grip is blued and i don't think that it was reworked. is this original? or must there be no blueing inside the grip? the firing-pin is completely blue! but not blued! in my luger-book i've read that the top of the 1934 firingpins were hardened till they were blue, but can it be, that the complete pin is blued by hardening? all numbers are sharp and not reworked. the blueing of the knee seems black, is that right?