Contact the guys at Wilson Combat. A friend from this form had his worked by them and that gun is pure delight!!! http://wilsoncombat.com/new/custom-beretta.asp#.Vaf_1_lVhBc
Also if you dont want to spend too much money and get excellent work I sent mine some time ago to Ortiz Custom guns in Savannah, Ga. The owner is one hell of a gunsmith, he is the one that works on my competition STI's.