Colt Knost is comfortable here.

Growing up in Pilot Point, Texas, Knost played nearby Lake Kiowa Golf Course -- a short, tight layout. He didn't pick up the game until age 14 but learned to love playing the precise shots that are serving him well this week at Harbour Town Golf Links.

The 26-year-old fired a 5-under 66 Friday at the RBC Heritage Presented by Boeing, taking advantage of a favorable tee time and tamer conditions than Thursday to get to 9 under after two rounds. He leads by two shots over Carl Pettersson.

Two-time champion Boo Weekley is another shot back at 6 under after matching Knost's 66.

Knost is halfway to one of his goals, halfway to winning a PGA Tour event after turning professional as the country's top-ranked amateur in 2007, when he won the U.S. Amateur Public Links and U.S. Amatuer in consecutive months. He won twice on the Nationwide Tour in 2008, finished No. 6 on the money list to earn his PGA Tour card the first time. He lost his card in 2009, earned it back on the Nationwide Tour in 2010 and lost it again after the 2011 season.

"I felt like I was ready for this level out here, and apparently I wasn't," Knost said. "I don't know if I just didn't continue with the same work ethic or not, or I didn't have the belief, but it was a struggle for a few years out here. But now I feel like I'm starting to get my game back where I like it."

More benign conditions greeted golfers Friday after the opening round played the second toughest of any on tour this season. Scoring was more than a stroke better Friday -- 71.92 after players averaged 72.96 Thursday.

Defending champion Brandt Snedeker fired off five consecutive birdies on his way to a 30 on the front side. He was 2 over on the back and is tied for seventh.

Former University of Georgia golfer Harris English, who won on the Nationwide Tour as an amateur in 2011, posted a second straight 68 and is tied for third with Weekley at 6 under. English holed out from a bunker on No. 8 for birdie after coughing up a shot the previous hole.

The conditions allowed players to better attack a firm golf course, English said.

"We'll see if it picks up this afternoon, but it was perfect this morning," he said.

Charley Hoffman, in danger of missing the cut through 11 holes Friday, closed with four consecutive birdies to shoot 65. That matched Pettersson for the low round of the tournament until Michael Bradley posted 64.

Pettersson said his iron play hasn't been sharp in recent years but has improved in recent weeks. He hit his approach within 5 feet on his final two holes.

"It certainly is nice to be right on top of my game," Pettersson said. "You obviously want to win, but all you can do is give yourself a chance."

Knost crafted a bogey-free round, creating a cushion with birdies at No. 1 and 2 after making the turn.

Knost cried after the final hole of PGA Tour Qualifying School this past December, thinking a double bogey at the last cost him his card. But a tie for 27th was good enough to earn his ticket. And he's back on the big tour, working with sports psychologist Neale Smith to help maintain his consistency.

Knost has made seven of nine cuts to start 2012.

"I got kind of lucky there at Q-School, and I was emotional about it, and I'll be the first to admit it," Knost said. "My caddie said, 'This is going to make you better.' And I feel like it has."