Branshaw temporarily held the lead and the course-record as he got in the clubhouse first with 61, to finish at 16-under. Patrick Sheehan, who had set the course mark of 62 on Thursday, is 14-under-par and fell to third place. Rob Bradley and Shane Bertsch are one stroke behind Sheehan at minus-13.
Gore matched the Buy.Com Tour's all-time 36-hole score of 125, set by Jeff Freeman in the final two rounds of the 2001 Fort Smith Classic. The players will now shoot for the Buy.Com tour-record of 26-under-par, first set by Chris Smith at the 1997 Omaha Classic and matched by Todd Barranger at last year's Dayton Open.
'With this golf course, anything can happen,' said Gore. 'The greens are so good you just have to get the ball moving forward on line and it'll go in. Somebody can come out and shoot 61 on me tomorrow.'
Gore, who has won twice on the Buy.Com Tour this season, started on the back nine at the Whirlwind Golf Club's Devil's Claw. His round started slowly with birdies on 11 and 15. However, Gore jump-started his round with an eagle on the par-5 17th.
'I've tried to realize that you don't have to play perfect golf all the time,' Gore said. 'You don't have to hit every shot perfectly. All of a sudden you start believing you're good. You start believing in yourself. I don't know what I'm doing and I don't want to know.'
After turning to the front side, Gore sank three consecutive birdies starting at the first. He then parred the fourth and fifth, before beginning another stretch of three straight birdies at the sixth.
'All I've been trying to do the last five or six weeks is keep it going,' said Gore, who posted his career-best round. 'You can't get ahead of yourself. It's just staying in the moment and adding them up at the end.'
Branshaw got rolling with consecutive birdies starting at the third. After a par at the fifth, he birdied three straight holes beginning at the seventh. Branshaw did not slow down after he made the turn.
Branshaw had back-to-back birdies at 12 and 13 and then closed with a flourish. He birdied 16 and eagled the par-5 17th to close out his 61.
'You're not that fearful out here this week,' said Branshaw.
Gore and Patrick Moore, who is tied for 12th at minus-10, are two of the four two-time winners on the Buy.Com Tour this season. Cliff Kresge, who is tied for 19th at 9-under, and Arron Oberholser, who missed the cut, are the other two-time winners.
If one of these four were to win and become a three-time winner, that person would get the automatic Battlefield Promotion to the PGA Tour. Four players have previously gained this promotion -- Smith in 1997 and Heath Slocum, Chad Campbell and Pat Bates in 2001.
Anthony Painter, Charles Raulerson and Barranger are tied for sixth place at 12-under 130. They are one stroke clear of James McLean and Chris Couch.
Moore is tied with Doug Garwood, Kevin Durkin, Jason Dufner, Vic Wilk, Victor Schwamkrug, Kelly Gibson and Dave Schreyer at 131.
Full-field scores from Gila River Classic