Brigman, whose only Nationwide Tour win came at the 2003 Permian Basin Charity Golf Classic, completed 36 holes at 13-under-par 131.
Jarrod Lyle, one of three first-round leaders, carded a 5-under 67. He is in second at minus-11. Chris Smith posted his second straight 67 and is alone in third at 10-under-par 134.
Brigman poured in eight birdies over an 11-hole stretch to fly into the lead.
He began his run at the par-4 fourth with his first birdie. He made it two in a row with a birdie on the fifth at Fox Den Country Club .
Brigman made par at the par-3 sixth, before he ran off three straight birdies from the seventh. At the 10th, he birdied the par-5 to get to 11- under.
After a pair of pars, Brigman converted a birdie effort on the par-three 13th. He came right back with a birdie on the 14th before parring the final four holes.
'That was a huge up-and-down for me on fifteen,' said Brigman of his up-and- down par on 15. 'The key has been momentum this week. A couple of times I got up-and-down yesterday for par and kept my momentum going. Today, I made the putts to keep it going.'
Lyle was hot early with three birdies in his first four holes from the 10th, his first. He moved to 10-under with a birdie at the 17th.
Around the turn, Lyle got to minus-11 with a birdie on the par-5 first. The Australian dropped a shot on the par-3 sixth, but recovered that lost stroke with a birdie at the eighth.
'Two shot's back is a good place to be,' Lyle admitted. 'I'm going to be the one chasing and that's where I like to be. I don't want to count my chickens too early, but I'm in a good position.'
Matt Weibring and Wade Ormsby both carded 5-under 67s Friday to move into a share of fourth at 9-under-par 135.
Chris Kirk and Arjun Atwal shared the first-round lead with Lyle. Both posted 2-under 70s in the second round. They were joined in a share of sixth place at minus-8 by Greg Chalmers, Doug Barron, Brad Fritsch, Spencer Levin, Reid Edstrom and John Kimbell.
The cut line fell at 3-under-par 141 with 65 players moving on to the weekend.