Barnes was joined at 6-under-par 136 by Marc Leishman, who carded a 5-under 66 in the second round, which was played under preferred lies.
Josh Broadaway is alone in third at minus-5 after a 3-under 68.
First-round co-leaders Fran Quinn and Chris Nallen both shot even-par 71 Friday and slid into a tied for fourth at 4-under-par 138. They stand alongside Gavin Coles (69), Darron Stiles (70), Vance Veazey (69) and Bryce Molder (69).
Barnes played the back nine first on Friday and got off to a hot start. He poured in three consecutive birdie chances from the 12th to jump to minus-2.
After a par on the 15th at Miccosukee Golf & Country Club, Barnes connected on back-to-back birdie tries from the 16th to turn in four-under.
'I had just made six birdies in a row ' well, 15 was a par but it felt like a birdie ' and then got it up and down at 18 to keep my momentum going,' Barnes said.
He birdied the fourth and seventh to gain a share of the second-round lead.
Barnes wants to make sure he finishes in the top 25 on the money list, which would give him his PGA Tour card for next season.
'You still have to finish off the year,' said Barnes, who is No. 21 on the money list. 'I'm not going to be content until I'm in the top 10. That's when you feel secure. I was in good spots all day and never got behind the eight-ball.'
Leishman, who won the WNB Golf Classic two weeks ago, also started on the 10th. After a birdie on No. 10, he sank birdie efforts on 13 and 14 to move to 4 under.
The Australian parred five straight around the turn before stumbling to a bogey on the par-4 second. Leishman bounced back with a birdie at the fifth, then birdied seven and nine to join Barnes in the lead.
'I've been hitting my wedges close, but the putter's been the key this week,' said Leishman, who turned 25 on Friday. 'I'm still trying to get the ball in the hole, just like everyone else. I'm just doing it a bit quicker these last few weeks.'
Scott Gardiner, Andrew Bonhomme, Tom Gillis, Matt Bettencourt, Matt Hansen and Chad Ginn share 10th place at 3-under-par 139.
The cut line fell at 2-over-par 144 and with this being the final full-field event, several players will watch the results this week to see if they remain in the top 60 on the money list. That would get them into the field at the Nationwide Tour Championship next week.
Among those who missed the cut were, No. 55 on the money list, Joe Daley (145), No. 57 Cameron Percy (146), No. 56 Henrik Bjornstad (148), No. 54 Tee McCabe (152) and No. 60 David Hearn (152).