I have a Beretta SO5 target gun with Bohler Antiknit barrels. About an 1/8" of the top rib came loose at the joint between the monoblock and the top barrel. I sent it to the official Beretta mechanic in the official New York City Beretta store. When it came back I was able to shoot about a flat of shells through it before it came loose again. Sent it to Cole's. About three boxes before it came loose again.
I gave up and just shoot it like that now. Apparently the ribs on stainless steel barreled Berettas are hard to repair.
Your mileage may vary.
Best,
Mike