Tonight I decided to wipe the Spike’s Tactical 5.45 down with a rag. I don’t have any photos yet, but I couldn’t find any corrosion on any of the upper receiver components. The fire control group and the safety – which had standard finishes, not the Melonite and Nickel Boron that the upper received – had moderate amounts of pitting. Edit: These components were not manufactured by or acquired from Spike’s Tactical. Spike’s does offer a Nickel Boron plated fire control group – it would be a good choice for this upper.
It’s been just under a month since the first rounds of corrosive surplus were fired through the weapon. I wasn’t surprised at the results, and expect excellent corrosion resistance for the foreseeable future.