COTABATO CITY —Three town mayors in Maguindanao del Sur have surrendered six high-powered firearms, including a caliber .50 machine gun, yielded by their constituents, officials said. Brig. Gen. Ricky Bunayog, acting commander of the Army’s 6th Infantry Division (ID), received the loose firearms collected from the municipalities of Shariff Aguak, Ampatuan and Sultan sa Barongis on Saturday, as part of continuing efforts to maintain peace and sec…