MOSCOW, 4 Sept 2015, (AFP) - The Welshman's more or less faultless second round 66 began when he picked up three shots in the opening four holes before another birdie ahead of the turn.
He added another birdie on his back nine before safely parring the closing six holes for a 10-under par total of 132.
Dredge said: "For me the highlight has been the putting, I’ve been putting really well.
"If I could get two more rounds of 66 that would be tough to beat but it’s only halfway through."
Slattery staged a remarkable recovery to add a second round of 67 to his opening 66.
After carding two bogeys in his first 10 holes on Friday, the 37-year-old Englishman shot five birdies on the back nine to head into the weekend on nine under.
Australia's Daniel Gaunt, who held a share of the overnight lead, is a shot further back on eight under after carding four birdies and two bogeys on his way to a two under par 69.
Leading second round scores in the EPGA Russian Open at Skolkovo Golf Club Moscow on Friday (GBR & IRL unless stated, par 71):
132 - Bradley Dredge 66 66
133 - Lee Slattery 66 67
134 - Daniel Gaunt (AUS) 65 69
135 - Ben Evans 67 68, Estanislao Goya (ARG) 68 67, Pablo Martin Benavides (ESP) 68 67
136 - Jason Scrivener (AUS) 70 66, Craig Lee 67 69, James Heath 70 66, Scott Jamieson 65 71
137 - Jacques Blaauw (RSA) 71 66, Jordan L Smith 69 68, Maximilian Kieffer (GER) 68 69, Javier Colomo (Spa) 69 68, Sebastian Garcia Rodriguez (ESP) 70 67, David Horsey 67 70, Matthew Southgate 68 69, Simon Wakefield 69 68, Daniel Vancsik (ARG) 69 68, David Drysdale 68 69, Cyril Bouniol (FRA) 68 69, Keith Horne (RSA) 67 70, Oskar Henningsson (SWE) 69 68, Jerome Lando Casanova (FRA) 69 68, Chris Lloyd 69 68, Michael Hoey 71 66
138 - Thitiphun Chuayprakong (THA) 67 71, Danie Van Tonder (RSA) 69 69, Panuphol Pittayarat (THA) 67 71, Matthew Nixon 68 70, Oliver Farr 71 67, Chris Doak 71 67
139 - Prom Meesawat (THA) 68 71, Peter Erofejeff (FIN) 73 66, Lasse Jensen (DEN) 70 69, Andrea Pavan (ITA) 70 69, Ryan Lynch (AUS) 69 70, Simon Griffiths 68 71, Johan Edfors (SWE) 71 68