rharfo, this is copy of Dakota 2012 price list
Dakota Arms Price List 2012
As you see no listing for a 280AI but the do custom chambering at extra cost.
That rifle may of not been ordered as SAAMI spec 280AI or build as one. I know Gulf Breeze handles some of their custom chambering and sure they were order that way by them.
you need to find out what chamber you have and go from there.