For input & topics about sound reduction or surpressors, I would look here;
www.Silencertalk.com .
For barrels & threads I'd check out Irv Stone's highly rated Bar-Sto, KKM, Jarvis or maybe Storm Lake.
Ciener & Knight's Armament in central Florida make cans & sound reduction gear but I'm not sure of the other top companies for the M9/92FS pistol line.
Good US pistolsmiths for Beretta 92 series pistols include David Sams, Ernie Langdon & David Olhasso(check spelling).
CF