Both sides competed bravely in the opening quarter of the game, but Ricky McIlheron, operating at 10, split through the defence and sidestep round a would be defender before offloading to No.8 McCluggage to get the opening score of the day.
Armoy scored before half time to level the score line.
With Armoy creeping up the pitch, it was a fiercely contested scrumming game for both packs, but front row of Adair, Smyth and Johnston for the home side, soon got the upper hand and stole the ball from Armoy's grasp.
Things went from bad to worse for the Armoy men when their captain was sin binned for taking the man out from a quick tap penalty, and Ricky McIlheron danced through to score Larne's 2nd of the day.
Josh Miller, playing his debut for the 3rds, finished off a well executed wide ball from the backs to score left of the posts. Unlikeliest of kick takers McCluggage, opted to take the conversion and booted it straight between the sticks to a standing ovation from the Larne home crowd.
Armoy hit back late into the second half to keep in contention of the game with 2 worked tries from the big forwards, carrying the ball over the line.
Larne managed to get another score on the board via McCluggage and held out the Armoy fight back before the final whistle blew.
Final score 26-19.
Larne 3rds: R. Adair, S. Smyth, S. Johnston (c), R. Jones, J. McNee, J. Reynolds, P. Castle, J. McCluggage, R. McDowell , R. McIlheron, J. Miller, R. Gabbey, A. Murray, C. Burleigh, A.Gibson, B. Meikle, M. Gilbert, J. Murphy