Inspired by
@ct71rr before and after, I just did a choke assembly in the the citric acid solution. I could have soaked it longer, and gotten it cleaner, but I was in a hurry to make these photos. I soaked for about 2-hours at 65*F ambient
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edit: If these results seem dramatic, bear in mind it's all about the severity of the rust on the part being treated. The guy in the youtube video
is conducting tests on lightly rusted sheet metal. They will come out pretty nice no matter which treatment regimen he uses.
I will post something soon, on a more heavily (and thicker) rusted part, to show the results (hopefully good) but less dramatic.
The choke assembly (pictured above) looks dark and severe, but the rust wasn't that bad. It wasn't that thick, or very deep (in terms of microns). But I will go on record and say this: if there is a shiny metallic surface to be saved, to be preserved, the citric acid solution from the youtube video does a better job than many other (phosphoric acid) OTC products.