P.J. Cowan, Kevin Muncrief, Andy Sanders and Ron Ewing are tied for third place at 4-under-par 138.
Bohn began his day on the back nine at DiamondBack Golf Club and four shots off the lead. He got off to a quick start with birdies at the 11th and 13th before he closed out a solid first nine with a birdie at the par-5 18th.
Around the turn, Bohn stumbled to a bogey at the second. Bohn erased that mistake and more as he ran off four consecutive birdies from the fourth to move to minus-7.
'I played real well today and didn't make many mistakes,' said Bohn. 'My game is improving. I just try to take one shot at a time and hopefully that will put me in contention on the weekend.'
Allen had an inconsistent round while also starting on the back nine. He struggled out of the gate with a bogey at the 10th. He recovered with birdies on the 12th and 14th to get to minus-4.
The 1998 Greater Austin Open winner dropped back to 2-under with a double-bogey at the 17th. He recovered one of those strokes with a birdie at the 18th.
'I played an up-and-down round today,' Allen said. 'Today was one of those days that could have been 75 or 64. It could have been anything.'
Allen fell back to one-over for his round with a bogey at the first. He rebounded nicely with back-to-back birdies from the third. He jumped to 6-under with an eagle at the par-5 fifth and then grabbed a share of the lead with a birdie at No. 6.
'The cup was looking pretty big on those holes,' said Allen of his hot streak. 'It was a great stretch because I really wasn't playing that well.'
Blaine McAllister, who won the NE Pennsylvania Classic two weeks ago, and Jay Delsing are among 15 players tied for seventh place at 3-under-par 139.
Overnight leader Jim McGovern struggled to a 3-over 74 and dropped into a share of 22nd at 2-under-par 140.
The cut line fell at 1-over-par 143. Among those who will not be around for the weekend are Roland Thatcher and Pete Morgan, who had both opened with rounds of 2-under 69, as well as local favorites David Morland IV and Richard Zokol.