Here is a scan of the part in question.
It may be a bit difficult to make out, but this is not the usual angled dovetail. The cuts are straight, almost making a tab-in-slot sort of insertion.
I have to wonder if the part is not an extreme press-fit, and the effect we see on the guns is simply the same kind of compression effect as halo from stamping? If it was silver solder I wouldn't expect to see any evidence beyond the actual part juncture.
Maybe Lugerdoc can answer this, when the toggle lock is removed, does it simply press out, or does it require heat to melt silver solder?
--Dwight