Mauser Barrel markings

Hey guys, it has been awhile since I opened up my Mauser, and I had a few questions I didn't get answered yet. Anyways I'll get to it, I have a '42 ce coded Mauser. It has some barrel markings under the the barrel between the receiver and the rear sight. I haven't been able to figure out what they mean as of yet. I have taken new close up pictures of them (posted below). I was curious if one of you guys could shed some light on what they mean. I also have a question about the rifle's bluing, oddly the rifle's receiver has turned an odd plum color except for one stripe, what does this mean?