Southern Force batted first and finished at 6/295.
Ben Bullimore smashed an unbeaten 107 runs off just 88 balls for the Force.
Bullimore was ably supported by Brad Davis (83) while Nosiana Pokana (2/63) and Norman Vanua (2/68) were the wicket-takers for the Barras.
In reply, the Barras got off to a steady start with Tony Ura (23) and Lega Siaka (30) taking the score to 3/79.
Captain, Assad Vala (57) and Sese Bau (75) put a century partnership for fourth wicket, shifting the momentum in the favour of the Barras.
The dismissals of Mahuru Dai (31) and Dogodo Bau (18) later in the innings left the Barras in trouble at 7/257.
But John Boge Reva (24*) and Norman Vanua (18*) were able to guide the Barras home to victory with 22 balls to spare.