Interesting.
SWDinc.com (A company that sells gun blued fasteners) indicates that hot blueing creates Fe3O4 (Magnetite) at/into the surface of the steel. Magnetometer is a rock that is magnetic......
This is really interesting with respect to a thread about a magneto-something or other velocity measuring tool, (vs. a chronograph) which some fire members have said degrades accuracy....
But that is another topic.
The sit also says that "black oxide parts have improved publicity and anti-aging characteristics due to the after-finish (oil or wax) resulting in smoother running, mating parts."
So based on the statement of a company who gets their business from the superiority of black oxide fasteners, it is still the oil which makes bullets pass more smoothly through your bore....
Hope this helps.
