Here is the deal. At 25 yards, the gun still shoots about 3 inches left and the rear sight is moved all the way right. It cannot go any further- out of adjustment space. The gun shoots left from 25 yards and in, but at 50 yards it is centered the way it should be, albeit low.
Does the shooter have a canted front sight assembly? That was my thinking before he shot it at 50 yards.
The gun involved is a Colt 9mm SMG. Nothing done to it, no custom work or anything. My recommendation to him was to have it sent back to Colt- good idea or can it be fixed locally?