That's a great suggestions. I still have some RPM that I'll try your idea with. Scott Smith (Harms) also suggested with the SEM bolts (captured washers) that a soak in Evaporust after the wire wheel / media blasting might get even more of the rust off from under the washer. Then a quick rinse and dry off before the Black Oxide should work really good.

Both those ideas are great. Thanks for sharing those! I love to learn new ways to do it.