Allred fired a 6-under 66 at Cliffs Valley, one of three host courses this week, while Gainey had a 1-under 70 at Walnut Cove. The duo was tied at 8-under 135 overall.
Richard Johnson played the third course, Keowee Vineyards, and had a 2-under 69 to share third place with Peter Tomasulo, who shot a 3-under 69 at Cliffs Valley. Johnson and Tomasulo were at 7-under par, one shot off the lead.
Chez Reavie (69, KV) and first-round leader David Hearn (74, WC) were tied for fifth place at 6 under.
Historically, this is a good weekend to challenge on the Nationwide Tour.
The last six winners of this event are all currently playing on the PGA TOUR, including last year's champion, Ken Duke, who ranked 22nd on the new FedEx Cup points list at the end of last weekend.
Between the leaders, Allred's round stood out. He climbed from a tie for 37th place overnight into a share of the top spot with a round that included seven birdies and just one bogey.
And he did it in windy conditions.
'Ever since I was a little kid I've enjoyed playing in the wind,' said Allred, who posted three third-place finishes in his rookie season last year. 'I love being creative on courses. On nice days I don't focus as well as I do on windy days. Playing in the wind forces you to be more creative.'
Gainey, a former competitor on the GOLF CHANNEL series 'The Big Break,' had two birdies and a bogey in the second round. He hit just nine greens in regulation Friday after riding an accurate streak to a 65 at Cliffs Valley on Thursday.
A 10-foot par putt at the 18th hole helped him maintain a share of the lead.
'That was huge for me,' said Gainey, who was known as 'Two Gloves' on 'The Big Break IV: USA vs. Europe.'
'It was great to finish the day with an under-par score and to have a share of the lead ... I couldn't be happier. This is a great position to be in. I am excited to get out there and give it a go tomorrow.'
In addition to the Nationwide Tour professionals playing this week, there are also a host of celebrities competing in the Pro-Am, including actors Kevin Costner and Greg Kinnear; and professional athletes John Elway, Wayne Gretzky, Brett Hull, Jim Rice and Sterling Sharpe.
Gary Player, the 71-year-old Hall of Famer from South Africa, is also playing for the fourth year in a row. He shot a 5-over 76 Friday at Keowee Vineyards and was in second-to-last place out of 168 players.
The cut will be made following the third round.
Cliffs Valley will host the final round Sunday.