I was north of there a year later... It was possible back then to trade for or buy a variety of weapons if you were in rear areas - so you might run into almost any sort of odd materiel... I kept a sawed off shotgun with a musette bag with a hundred rounds just for my jeep to keep anyone from jumping on board (I was out and about occasionally by myself.... just south of Hue). NO it wasn't a particularly good idea - and I didn't learn until years later how little I knew about shotguns or tactics back then... Any time we came into contact with spooks, though, we always knew who they were just by their weaponry (they were the only folks in my area that had Uzi's).
I pretty much figured anyone actually using weapons in regular units wouldn't ever have bothered with some of the exotic stuff you'd find in rear areas - but I could be wrong...
Remember the accepted figure during that era was seven personnel in rear areas for every one actual combat soldier out on the pointy edge of things...