The 61-year-old, known as Louis around Ochilview where he played in the mid-nineties, took the 100m handicap title at the St Ronan’s Games at the end of last month.
The former Stirling Albion, Berwick Rangers and Stenhousemuir footballer kicked off his afternoon with a comfortable win in his heat in 10.72 seconds from a mark of 18.5m.
He was then beaten in his cross tie by Corey Wilson of Hawick (11m) in 10.49 seconds but qualified for a place in the final by coming in second.
Armstrong was bidding for his third St Ronan’s sprint success as he had previously won the event in 2008 and 2010. Wilson, TLJT pair Marshall Smith (13.5m) and Tommy Finkle (14m) and David Hush of Hawick (22.5m) all had to be beaten for him to notch up a hat trick.
Seasoned campaigner Armstrong was hungry for his hat-trick and duly produced his best run of the day when racing to a photo finish win in 10.27 seconds, the other placings going the way of Finkle and Hush.
Armstrong said: “I have been running well since the season started and things have been going great at training and I thought I might have a chance of doing something.
“I am really chuffed to have pulled off a win. It’s the third time I have won the St Ronan’s sprint in seven years.
“The fact that it is a downhill track might help.”
Armstrong was part of Stenhousemuir’s historic Scottish Challenge Cup winning side of 1995.