The rear sight is an LPA - all steel, made in Italy but available in the USA through several suppliers - maybe even S&W as a service part as they use them on the Competitor line (although not the fiber optic one as shown on this gun).
IIRC, there was a fellow from Italy, that posted on this board, that made barrel weights like the one shown. Did this picture originate in Europe? The Nills, LPA and weight would indicate that as a possibility.
Adios,
Pizza Bob