The finish on all of mine has been a little rough also. Never had a problem with the weather though as mine have been sealed from the factory. As far as the barrel being centered in the forend, my 280 was like that. I just loosened up the 2 screws, centered the barrel and then had a buddy tighten the screws back up. No problems at all . . . the barrel has stayed centered every since. I have seen quite a few free floated rifles with this situation. The problem is when the barrel channel is so tight that it cannot be remedied without sanding.
Long