A Hastings club member had sold her a rifle within three weeks of engagement and she has never looked back.
"I pretty much live there now [club], training six days a week."
That tangential shift in life had earned Birrell the honour of leading her country, on debut, to shoot against the UK Home Counties team by postal shoot a day after her first indoor shooting competition. The postal shoot results are pending.
That privilege to captain the New Zealand women's side came a fortnight ago after the 34-year-old emerged as the top gun from both her North Island team and their South Island counterparts during a shootout at the Manawatu Smallbore Rifle Association range in Palmerston North.
In March, she competed at the outdoor nationals in Christchurch where she finished ninth overall in an open field of 50 but was the fourth best female shooter. She had made the top-20 and top-22 NZ Open teams as well as the top-five NZ women's side.
North Island stamped their supremacy in clinching the junior, veteran, women and open grades. The veteran and women posted record scores on 10, 20 and 10-shot targets.
Christopher Harrison, from the Ruahine Smallbore Rifle Club, and fellow Waipukurau enthusiast Luke Sigvertsen, from the Dannevirke Smallbore Rifle Club, were members of the North Island open team with the latter bringing home the shield as captain.
Harrison also will be making his debut (having received his NZ pocket) for the New Zealand open team to face off against the UK Home Counties side.
Luke Sigvertsen, as captain of the winning Open team, has brought home the North v South Island Open Shield as champions.
When Birrell shoots she totally immerses herself in the process to the extent she becomes oblivious to everyone and everything in a code where controlling one's heart rate is imperative and which demands a different type of fitness.
So much so that her mind and soul are honed towards that one speck of black target.
"It's the precision of it where you're trying to take out a millimetre dot, which is essentially a tiny black dot which is metres and metres away but you're trying to do it over and over again for a perfect score."
She fits in her hobby in her shift work on week-day nights as well as weekends.
"I try to decide whether to train or exercise so training kind of wins."
Birrell managed 199.18 and 198.12 out of a possible 220, which came agonisingly close to bagging her two perfect scores.
"I'm getting closer and closer all the time."
Outdoor shooting is staged through summer over 50m and with 60-shot matches in the face of factors such as wind. It is part of the Commonwealth Games discipline but has lost its place in the Summer Olympics.
"It's a lot more harder and takes a lot more stamina and you have to deal with the elements."
The indoor format is over 22m in 10 to 20-shot matches staged during winter, which negates the impact of wind.
Birrell has made the cut for the 50m Oceania outdoor team and the 10m air rifle event indoors although the latter is performed standing rather than lying prone.
"The standing shooting's quite technical because you're in pants, jackets and all sorts of stuff, standing for an hour just shooting."
The air rifle is held in a fist before it's fired.
She is in the process of clearing some paperwork for what is her first trip overseas to compete in the Oceania Championship - which doubles up as 2018 Gold Coast Commonwealth Games qualifiers for Kiwis - in Brisbane later this month and early next month. Birrell is not in the equation for the Gold Coast Games, from April 4-15, despite her meteoric rise in a relatively short time.
"It's just because other people have been shooting for a longer time at a consistently higher level over someone like me."
However, four years on, she fancies her chances provided her scores remain up there.
"I'm still climbing the mountain to get to the top."
So has Cupid struck Birrell in the heart with his arrow again?
"Oh I'm a much happier person now but I'm still single."
A laughing Birrell says she's still trying to zero-in on the right bloke before pulling the trigger but, for now, when she looks down the barrel of her gun via the aperture sight, she finds traction with "like-minded" people who create a fantastic environment to fulfil their passion.
