"I had a stint at Karamu High School before heading off to university but that was it before getting back into it two years ago," replied the 33-year-old Hawke's Bay Hospital Medical Lab scientist.
In Christchurch, where she shot outdoors and over 50 metres, Birrell won her aggregate score section by 13 points with 576 out of a possible 600.
On the Thursday afternoon Birrell shot a personal best 589 out of 600 to be the best C grade shooter overall with eight blokes finishing below her.
Her 589 was the third best score on the Thursday afternoon across all grades.
Birrell was the seventh best woman with a score of 580 in the International Sports Federation's match shoot on the Friday.
With all of her scores added together she qualified fifth overall among the Kiwi women and was selected for the Wakefield team which catered for the top 10 Kiwis and the Slazenger team which catered for the top 22 Kiwis.
While the Slazenger team competed against Australia, the Wakefield team took on Great Britain, the United States, Australia, South Africa and Canada in postal shoots.
"We're still waiting for results from other countries to see where we finished up. Everybody in the Kiwi team ahead of me were all A grade shooters with Commonwealth Games or other international experience. This is what has inspired me to strive for that level ... next year is obviously too soon but 2022 is realistic," Birrell, who shot 583, said.
At the end of the nationals she combined with Dannevirke's Robbie McNair and Waipukurau's Luke Siegvertsen to form a combined Hawke's Bay-Southern Hawke's Bay team which won the graded teams match.
The self-coached Birrell, who will be a B grade shooter when the next season starts at the end of September, pointed out numerous training sessions and trips to competitions out of the province have been instrumental in her success.
"I go to Norsewood at least twice a week. I call those sessions my wind-training ones because it is always windy there," she said with a laugh.
Birrell competes at Bay View on Saturday mornings and visits the Tokoroa, Palmerston North and Lower Hutt clubs regularly. She returned from her last visit to the Lower Hutt club with two championship trophies.
While her determination in all the events she tackled in Christchurch is admirable Birrell is equally as determined as an air rifle shooter.
Despite just six months' experience in this discipline she recorded a top eight finish in the recent Palmerston North-hosted air rifle nationals.
"Air rifle is upright. The rest of my disciplines are done lying down. I want to get to a good level doing both," Birrell said.
The Christchurch trip is an indication she is definitely on target ... if you'll excuse the pun.
