Attached is a photograph of a 1980 or 1981 model 700 Remington LA magnum bolt with a crack completely around the bolt body. In the period of this bolt the boltheads were pinned and soldered to the bolt body. It is not cracked where the pin goes through but clearly the solder joint is cracked. Is it safe to continue shooting. The lugs are still solid.
To the OP. I was thinking file marks but a sander could have done it.
On the bolt pictured here. That is just sanded or worn down till the silver solder joint is exposed. It doesn't look cracked. No safety issue at all. It will go away if you Cerakote it. Even if it came loose it would still work just like a Savage floating head assuming it rotates into place. I have never seen a pin holding them. Just the solder. On current production the bolt heads are still soldered as far as I know. Same as the handles. On the OP 's bolt you can see the solder line on it too.