Duffy started at midfield for the Seasiders and helped his adopted club to an early 2-4 to 0-1 lead, with Armstrong hitting both goals. But despite their quick start, they only managed a 2-11 to 2-9 victory as Adrian Murphy hit the net twice for Kilcony.
Defending champions Corofin eased their way into the fourth round thanks to a 10-point crushing of Tuam Stars.
The champions lined out without Kieran Fitzgerald, Gary Sice and Ronan Steede, and had Aineas Lawless black carded in the first half, but still carved a facile 1-10 to 0-3 win at Tuam Stadium.
They led by 0-5 to 0-2 at half-time, but Mike Farragher’s goal in the third-quarter meant defeat for the record winners of the competition, who only managed one point in the second half.
Galway’s Eddie Hoare scored six points to help his club, St Michael’s to victory over Killererin by 0-13 to 0-6, while the Tribesmen’s injured full-back, Joss Moore, returned to action and starred for Mountbellew-Moylough as they defeated Menlough 2-15 to 0-7.
County minor midfielder Michael Daly scored the first goal while Cathal Kenny’s second just after the restart kept his side in control.
Annaghdown were in fine form once again on their way to a 2-10 to 1-8 win against An Cheathru Rua as goals from Damien Comer and Mathias Coleman saw them home.
Caherlistrane defeated a Caltra side bereft of their prized asset, Michael Meehan, 2-14 to 1-7.
Galway hurling star Cathal Mannion, started for Caltra but an early Cormac Bane goal set Caherlistrane on their way and when Oisín O’Brien added to this with one of his own it was an uphill struggle for Caltra.
Galway star Shane Walsh was left out of the Kilkerrin-Clonberne side as they were defeated by Cortoon Shamrocks by 1-9 to 0-11.
A Joseph Donnellan goal at the start of the second half was the difference between the sides as Kilkerrin-Clonberne missed a gilt-edged opportunity from a free in injury time and they now face into a relegation dogfight.
A 1-4 haul from Galway forward Mark Hehir helped Milltown to an expected victory over St James by 1-12 to 0-14.
Johnny Duane and Eoin Concannon both started for the city and lodged excellent displays as James’ now face into round three after what has been a disappointing campaign to date.
Carna-Caiseal are facing into a relegation battle after they could only manage one point in a poor second-half showing against Micheal Breathnach, who were victorious by 3-14 to 1-6.
Marc Mac Fhlannchadha goaled for Carna-Caiseal early on, but Peadear Óg Ó Griofa and Peadar O Cionnaith goals before half-time saw Breathnach’s to the win.
Barna’s superior fitness levels told as they outstayed a Naomh Anna Leitir Mór side after extra-time to win by 2-20 to 1-13.
The teams were level nine times during normal time as Bearna powered home their advantage in the latter stages, scoring 1-7 without reply in extra-time after it had finished 1-13 each after normal time, Ryan Folan’s injury-time goal sealed the win.