Anyone know of anyone that works on Benelli NFA barrels?

I've an M4 Entry that I want to put a Silencerco Salvo 12 adapter on, but have had no luck in finding anyone willing to do it.

(& please do NOT recommend King Armory!! They had my barrel for MONTHS - I sent it in after a promising phone conversation, only to have them refuse to answer emails or calls. They finally sent my barrel back with NO work performed, citing "inability to find proper choke threading components". Whatever...)

So, anyone else??