Gainey just missed becoming only the sixth player in PGA history to card a 59 when he knocked a birdie putt just short on the final hole at the Seaside Course.
He ended at 16-under 264 for his first PGA Tour win -- one shot better than David Toms (7-under 63).
Furyk (69) ended two shots off the pace at minus-14, falling out of contention with a poor approach shot on the final hole that forced him into an unsuccessful birdie-putt try from the short rough.
Brandon de Jonge (65), D.J. Trahan (69) and Love (71) finished in a fourth-place tie at 12-under 268.