LeBrun's 61 broke Kyle Thompson's course record by one stroke and LeBrun's 36- hole total smashed Thompson's record of 130 from last year.
Chad Wilfong, who played with LeBrun, posted a 7-under 63 to move into a tie for second place at 10-under-par 130. Steven Bowditch, who won the Jacob's Creek Open earlier this season, also moved to minus-10 with a 65.
Anthony Painter, Tim Simpson, Jerry Smith and Jon Mills share fourth place at 7-under-par 133.
LeBrun, 27, was on fire right from the start, opening with birdies on the first three holes. He dropped in a birdie putt on the sixth and moved to 10 under with a birdie at seven. He then birdied the eighth to cap his second run of three straight birdies.
'It was a nice way to start, especially on Friday,' LeBrun said. 'I think my Friday scoring average is probably around 77 going into today. I started off with three birdies and you can't beat that. You get to 8 under and you're not thinking about the cut anymore, you're thinking about trying to win the tournament or getting yourself in position to win it.'
LeBrun stumbled to a bogey on nine to fall back to minus-10. The Floridian converted back-to-back birdie chances from the 11th and got to 13 under with an 8-foot birdie putt on the par-3 15th. LeBrun closed out his round with a 25-foot birdie putt at the last to set a new course record.
'It's definitely my best round ever,' said LeBrun, who has never been higher than tied for 18th after 36 holes in any of his 17 career starts on the Nationwide Tour. 'Chad and I were both feeding off each other, especially early on. We were both making so many putts.'
Wilfong matched LeBrun's run of three straight birdies from the first. He then dropped in a birdie on the fifth to start another run of three birdies in a row.
The 24-year-old parred his next five holes. Wilfong, who made the cut for the second time in seven career Nationwide Tour starts, stumbled to a bogey on the par-three 13th.
Wilfong converted consecutive birdie putts from the 16th to move into a tie for second place.
'I looked at him and said, 'What did you shoot?' and he said '61.' I just threw my card up at that point because 63 is no good,' Wilfong said of his talk with LeBrun walking off the 18th green. 'He played well. It was fun to be a part of it.'
Bowditch opened with a birdie on the first and sank back-to-back birdies from the fifth to move to 8 under. The Australian stumbled to a bogey on the seventh, but came right back to birdie the eighth. He then managed two birdies over his final nine holes to tie for second.
'I started driving the ball better, though I'm still making a few terrible swings,' said Bowditch. 'Because I'm starting to drive it good, I took driver on absolutely every hole I could today.'
First-round leader Brandt Snedeker struggled to a 1-over 71. He stands at 6-under-par 134 alongside John Merrick, David Morland IV, Jason Dufner and Charley Hoffman. Jason Gore, who won the Pete Dye Classic last week, leads a group at minus-5.
The cut line fell at 1-over-par 141 with 65 players moving on to the final two rounds.