Ty Tryon's youth was not served as a group of veterans, led by Brett Quigley at 10-under 62, took control at Endicott, N.Y.
Tryon, 17, coming off a first-round 65, shot 72 in muggy conditions at En-Joie Golf Club.
Quigley took advantage of the cooler morning to shoot a career-best round, one shot short of matching a tournament record. With a two-round score of 15-under 129, Quigley held a three-stroke lead over Mark Hensby and Jonathan Kaye.
Thursday's co-leader, Edward Fryatt, shot 68 to match Jim McGovern (66) at 11 under.
Quigley's 28 on the final nine tied a PGA Tour low for this season set by Davis Love III at Pebble Beach in February.
Tryon, of Orlando Lake Highland Prep, shrugged off a performance that left him eight strokes back.
"I showed some stupidness out there," Tryon said. "I'm not mad or angry. I'm a little disappointed. It's just the way it goes. I go out there and birdie the first hole (today) and I'm right there."
SBC SENIOR OPEN: Gary McCord and Dana Quigley shot 7-under 65 to share the first-round lead at Long Grove, Ill., and Bruce Lietzke struggled to 74 in his senior debut.
McCord, the CBS announcer who has two senior titles, birdied four of his first six holes on the Kemper Lakes course. Lietzke, a 13-time winner on the PGA Tour, turned 50 Wednesday.
Quigley is the uncle of Brett Quigley. "I'm much more excited about him leading at the B.C. Open than me being tied for the lead here," Quigley said.