DeCordso completed 36 holes at 7-under-par 137 at Kinderlou Forest.
Marco Dawson (68) and David Miller (70) share second place at 5-under-par 139. Jeff Brehaut, Scott Parel, Vance Veazey, David Mathis, Ben Bates and Bryce Molder are one stroke further back at minus-4.
DeCorso got off to a flying start with birdies on the first and second to move to six-under. He gave one stroke back as he bogeyed the par-5 fourth.
The 37-year-old atoned for that mistake with a birdie on the par-4 seventh. He parred three straight around the turn.
DeCorso traded a birdie for a bogey from the 11th. He birdied the par-5 14th to get to 7-under, then parred the final four to lead by two after two rounds.
'I'm actually happier with my round today than I was with yesterday's round, even though it was one stroke higher,' DeCorso stated. 'There were some tough pins. If you short-sided yourself, you could be in some big trouble.'
DeCorso has recently been revamping his swing and it has paid off this week. He has hit 27-of-36 greens in regulation and 19-of-28 fairways.
'I am learning to hit the golf ball a completely different way,' DeCorso admitted. 'I had developed so many bad habits. Now I'm hitting more fairways and greens, and my scoring average speaks for itself.'
Dawson carded a bogey-free round. He played the back nine first and birdied the 14th and 15th. After three pars, Dawson connected on back-to-back birdies from the first to get within two. He parred his final seven holes to end there.
Miller also played the back first. He posted birdies on 11 and 14, but those strokes were erased by bogeys at 16 and 18.
Around the turn, Miller parred the first five holes. He birdied the sixth and followed with a birdie at the seventh.
First-round leader Garth Mulroy stumbled to a 2-over 74. He was joined in 10th place by Ronnie Black, Grant Waite, B.J. Staten, Bill Lunde, Greg Owen, Andrew Buckle and Daniel Summerhays.
The cut line fell at 1-over-par 145 with 68 players moving on to the weekend. Among those who missed the cut was 2007 winner John Kimbell. That means there still has never been a player that has successfully defended his title on the Nationwide Tour.