I just received this piece of blued steel, a new part for a rifle. The part has a complete coating of light oil, and was wrapped up. Those splotches you see that look a bit like hard water spots do not rub off or rub out by an oiled patch. I have the same thing to a lesser degree on the side of the receiver of a new rifle I just received. On the pictured piece, a couple of these areas have an almost rust color to them.

What are these stains? How did they get there? How do I get rid of them? Should either the pictured item or the rifle I mentioned be returned for refinishing?

Not a gunsmith but looks like the parts were not hot enough to evaporate all the water and some spots were left that rusted. I would try some flitz metal polish and see if it does any good. Anything much more abrasive like steel wool will start to take the finish off although some get away with 0000 steel wool. You might try soaking with a penetrating oil like Kroil or transmission fluid for a day or two and then try.

I'd be asking these questions to the individual that I received the parts from, they certainly would be unacceptable to me....

Well, whatever it is, I've arranged to send the part back to its maker for repair or refinish or whatever.