The next generation Liberty pistol will likely be a double or triple barrel type of a derringer made completely from an engineered plastic like Delrin straight off a 3D printer.
Every part is plastic, even the firing pin will only have a metallic tip and will be of a metal less detectable to a scanner, non ferrous like aluminum, though for the first couple of shots its quite possible to actually use a plastic firing pin. Just need enough travel and strong enough main spring behind it. Its been proven that even the large low pressure case of the .45acp can be fired in a plastic barrel, and a triple barrel .22 would be a perfect close quarter pistol, no rifling, no traceable firing pin strike.
Well, if as you say the pin is tipped in soft metal (Al, Cu, Mg), the strike-mark would change after just a couple of firings. And anyway it could be replaced per your description of the design, with every use if need be.
Of course, by that stage of things, Obama's thugs would be murdering people out-of-hand just for having one.