again?
I thought we went through this before. The melting point in and of itself, has nothing to do with how good the gun is or isn't, it's merely a convenient hook to hang an antigun law on. Same as if we said revolvers with right hand threads on their ejector rods will be legal, but ones with left handed threads will be banned. The melting point thing was chosen for its propaganda value as the low melting point alloys are associated with "cheap saturday night special" in the public mind. As in all such cases, they don't want the issue decided by emotion an not clouded with facts.
The pot metals are a class of relatively low cost alloys primarily designed for easy casting. Since they are desigend for easy casting they have relatively low melting points. They are aluminum based with various other metals such as copper, tin, lead, and zinc as additives. They are not noted for their strength. They have often been used in children's toys and kids can be rough. Rightly or wrongly, they have become associated with the idea of "cheaply made". There is also a class of zinc based alloys that are similar but are not generally called "pot metal".
None of these alloys are even remotely close in strength to steel, titanium, or the aluminum alloys used in quality firearms.