Re the wrapped Mk1 FTR's, I've just been informed that the corner of the polythene sack thinggy was always(?) cut across showing where the bag was vacuumed out THEN sealed. But I've been informed that the vacuum seal lasted about 5 minutes or until it developed a leak where it was mishandled by the non-too careful Ordnance wallahs. Rifles sealed for the tropics have a charge bag of silica-gel inside.
Hope this makes things clearer..............
Hope this helps