I suspect they started to pull the guide mandrel out without loosening it. That would account for longitudinal scratches all right. It will almost certainly be safe to shoot, and I am at a loss as to a satisfactory "remedy" I would ask for. I would darned sure ask for a significant percentage of what they charged you for the choke work, etc. refunded. I would got to the top with this. Turnbull did not get their reputation, or have people willing to pay what they charge for doing stuff like this.