Barnstaple scored three tries but were defeated 36-17 at Weston-super-Mare in National League Three South West.
Barum had travelled to Somerset keen to put last season's disappointing away record behind them.
But they were well beaten by a Weston side who have started the season with two convincing victories and seem likely to be one of the challengers for the title.
Will Topps scored Barnstaple's first try, from a Steve Perry kick through, then made the break for the second, which Ryan Carter finished. Replacement Luke Berry was on the end of an overlap for the third soon after being sent on. Topps converted one of the tries.
Perry, the fly half and joint head coach, said: "It was very frustrating. We seem to play very well at home but we need to get better away from home."