Piercy completed 36 holes with a tournament-record score of 16-under-par 126. The previous record of 127 was set by Eric Hoos in 1991 and matched by Emlyn Aubrey in 1998.
Chris Anderson carded a 6-under 65 and is alone in second place at minus-13. Daniel Summerhays and Hunter Haas carded their second straight 65s to move into a share of third at 12-under-par 130. Summerhays birdied his first five holes, but collected one more birdie and 12 pars to close out his round.
The first round was completed earlier Friday after a lengthy weather delay on Thursday pushed things back.
Piercy, who completed his first round earlier Friday, opened his second round with a birdie on the second before he collected back-to-back birdies from the fourth to move to 10-under on the North Course at Crestview Country Club.
The 29-year-old birdied the eighth and came right back to birdie No. 9. After a birdie on the par-four 11th, Piercy dropped his only shot of the day at the par-three 12th.
Piercy rebounded with three consecutive birdies from the 13th to grab the lead at 15-under. He parred two straight before draining a birdie on the 18th to push his lead to three shots.
'That was definitely one of those feelings you wish you could have every day,' said Piercy of his 10-birdie round. 'It was one of those eerie calms.'
Anderson birdied the second and fourth to get his round going. He dropped in his third birdie on the par-three eighth that moved him to 10-under.
After five straight pars from the ninth, Anderson eagled the par-five 14th. He then closed with a birdie on No. 18 to end alone in second.
'We are all trying to be a little more positive,' said Anderson, who was a playoff loser earlier this year at the Nationwide Tour Players Cup. 'We figured out it's not as hard as we've been making it. We all got tired of playing bad and we know we're better than what we've been doing.'
First-round leader Tommy Tolles stumbled to a 2-over 73 and fell into a share of 24th place at 7-under-par 135.
The cut line fell at 4-under-par 138 with 61 players moving on to the weekend. Among those who missed the cut were Jay Delsing (139), Arjun Atwal (139), Keoke Cotner (142) and Casey Wittenberg (142).