That says to me that military surplus will only be admitted as a curio & relic if it is complete in its original military form. That at least seems clear enough. It would also be useful to see a response from BATF about rifles built on actions which have seen of military use even if they are of similar form. I'm picking you would need to ID someone in the organisation who can actually understand what is being got at here. The non firearms savvy types would probably never get their heads around this.

Steve