First round leader Mikes Downes continues to lead the field at 7-under, despite an up-and-down day in which he struggled and lost the lead before a strong finish regained him sole possession of the top spot.
'I was battling for the first nine holes and to bogey 10. I was really struggling and trying to hang in there,' said Downes, who finished with a 2-under 70.
Four late birdies by the Aussie, including one at the 18th, got his game straightened out as they head into the weekend.
'I hit a good shot on the par-3 11th which got things rolling and I went birdie, birdie, birdie to get things back on track,' he said. 'A birdie on the last hole was a good finish.'
Defending champion Stephen Allan posted a course record 6-under-par 66 to vault into a share of second place with Barnes.
Michael Wright, Peter Senior and Nathan Green are in a tie for fourth, two strokes off the pace.
1999 and 2000 champion Aaron Baddeley (74), along with 2001 champion Stuart Appleby (73), both struggled in the rainy conditions and sit in a tie for 37th and a tie for 20th, respectively.