Eventually credited with victories over twelve enemy aircraft, plus two probables and eight damaged, Barr became No. 3 Squadron's highest-scoring member. He flew a total of eighty-four combat sorties, twenty of them in one fortnight, and six on 16 June 1942 alone. His philosophy was that the P-40 was not a top-class fighter, but that its shortcomings "could be offset by unbridled aggression", so he resolved to treat aerial combat as he would a boxing match and "overcome much better opponents by simply going for them". Bobby Gibbes became No. 3 Squadron's commanding officer in February 1942, and made Barr his senior flight commander. Promoted to flight lieutenant on 1 April, Barr was raised to acting squadron leader and appointed to command the unit in May, barely six months after he commenced operations, following Gibbes's hospitalisation with a broken ankle. Barr had never sought leadership of the squadron, and felt that others were just as well qualified for the role. As a commander he delegated most administrative tasks to his adjutant but, contrary to normal practice, wrote letters to the next-of-kin of casualties himself.