It would require vast modifications on machinery p'robly not available , but then again , so did the ANM2 .30cal " stinger " , so one can never say never. More likely , however , would be that someone saw an air service mag on an '03 or on an A3 with an '03 triggerguard. This replaced the flat floorplate with a 20 rd extension floor plate. It held 25 rds , was basicly non-detachable in use , and looked a lot like a BAR mag , though longer in hight and narrower in width.
Chris