Be sure that you are not overtightening the front action screw. If you are screwing it down really hard, you will get inconsistent groups.
Inconsistent groups (tight group, then loose group, then tight group), generally have nothing to do with the barrel and action itself. It is almost always the bedding of the stock to the action, or the contact between the stock and the barrel, or the mounts, rings or scope.
If you send this back to Remington, I sincerely doubt that they will be able to fix your problem. They will just declare it to be within specs.
Hope this helps.
Mannyrock