Russian captured (RC) K98ks are basically part guns.
Ivan dissembled the Mausers acid dipped all the parts and dumped them into large bins reassembling them with what ever worked then electro penciling those newly mated parts with the receiver number.
They are not required to remain legally on the gun.
Some feel the gun is now best preserved as a Russian Captured K98k and left alone.
I do not share that feeling.
Remember, brass wool may not remove bluing but it also can not be blued once brass wooled.
I sand, steel wool whatever I need to to remove the elctro pencil.
On the bolt body I use a belt sander.
Right behind the drive wheel and before the flat steel there is a gap (with the sander turned upside down and secured) which one can push the curved bolt body into getting a nice even sanding that removed Ivan's tattoo!!!
Milled floor plates and trigger guards I also belt sand but stamped one I take more time using files/steel wool. emery paper etc.
There are a few cold blue products but Oxpho-blue is by far the best and I wire brush all the metal, action, barrel etc etc and after heating the parts with a small torch I use the Oxpho-blue via an old tooth brush.
I also sand out the number stamped in the stock, remove the Rusky shellac and oil the wood (To off set cleaning solutions, laminate stocks were not oiled per say).
But, because I have bought a number of these and restored them I have accumulated extra parts and I rearrange the parts to correct period for that year and make K98k.
After I reblue the K98k I wire brush it to re-age it giving it a WWII era finish
I do not weld over numbers and try to pass them off as anything but restored Russian captured guns when I have sold them.
Below is a picture of a completed restoration. I broke even with a lot of free work so there is no incentive to do this monetarily.