Murray, from Raleigh, North Carolina, birdied four straight holes Wednesday on his back nine, and took a two-stroke lead after 18 holes. Trevor Cone of Concord, North Carolina, and Geoff Drakeford of Australia each shot 68.
Defending Southern Amateur champ Zach Olsen from Memphis, Tennessee, opened with a 76.
Murray, who transferred from Duke to Arizona State where he will be a junior this fall, hit driver only three times so he could hit mid-irons into the greens. During his consecutive birdies, his longest putt was 7 feet.
The winner of the 72-hole event will receive a spot in the PGA Tour's Arnold Palmer Invitational.