Saw a deal some years ago where the guy made one from a common nail. It was too long, punctured the primer, blew the FP out and "nailed" the guy dead center in his forhead.
How did the 'firing pin nail" get out of the gun? Did the pierced primer blow the gun apart?
Sounds like BS to me, only firing pins I've ever seen leave a gun in over 50 years of intense shooting is the firing pin on a 1911 if the firing pin stop falls out for some reason.