A late and possibly irrelevant post to your superb work. I had a blob of Hi-Force 44 solder from a job lying on the bench for over a year and noticed it had no signs of tarnish, remaining quite shiny. I was finishing two rifle projects with NECG express sights and hadn't quite figured out how to put wire in the grooves. I disassembled the sights and using a narrow propane torch tip I heated each standing and folding leaf up and filled its groove with Hi-Force 44 in lieu of platinum. I had to be careful to not heat the folding leaf tensioner spring in the main part of the sight excessively. I did that by loosely gripping the sight in unprotected vise jaws to act as heat sinks. Two years from now platinum may seem like a much better idea. We'll see.
Dennis