I have a remedy for that that maybe some of you might be able to use. I have found that there are a ton of sheet metal screws that have been "flash" plated with zinc. The plating is very thin, but these screws are available in slotted and cross driver heads in oval and flathead styles. Also available in the panhead style and the 82° underside taper. I've used the panhead style here, but any of the "zinc plated" screws can be treated likewise: The screw on the left is a mystery, as it's not known if that screw ever had threads. It was used to hold the forearm iron onto an old single barrel .410 shotgun given to a grandson by grandpa. Someone took the forearm iron out to refinish the stock and the original screws became lost. So, some of the tapered, oval head sheet metal type screws were used. : Now, these zinc plated screws, if used as is, will scream "amature job" for sure. Several years ago i stumbled onto a means where the zinc plating can be dissolved off these plated screws: A quick 10 second dunk into a container holding Birchwood Casey's Aluminum Black will dissolve the zinc plating off, like right now. If left any longer in this solution, it will start to attack the threads and actually dissolve those away. Now, after the 10 second soak, sometimes you will find that the solution has not removed the plating in the bottom of a screw slot, or the intersection of the cross type screw head. When that happens I'll use a solution soaked cotton swab to dab it into the slot or intersection to remove the plating. When the screw(s) are removed from the solution they will be black, but I still prefer to dunk them in a container of Oxnate liquid bluing as available from Brownells for bluing touch ups: Something to keep in mind rather than sitting on the computer searching for what may never transpire.