For the points score championship, a maximum three points are awarded for hitting the target with the first barrel, two points for connecting with the second barrel and no points for a miss.
Each country contesting the international postal shoot is represented by an open team (25 members) and five member ladies, junior, veteran and super veteran teams.
All the New Zealand team members shot 100 targets each in March.
The scores are then collated in Australia.
Results of the postal shoot are pending until after England, Wales and Scotland have shot in July.
The Australian junior team triumphed in 2017 with New Zealand runners-up.
The last time the New Zealand junior team won was 2009 and 2007.
Mac has made a meteoric rise into the national U21 team, having only taken up the sport in late 2015 when he and his dad started out at the Waikato Gun Club.
Mac switched codes because he could no longer play rugby after injuring his back playing lock for Te Awamutu Sports 13th grade team.
"I love duck shooting and always wanted to get more (duck) than dad each season so we thought let's give clay target shooting a crack," he said.
"We are now members of three clubs, Pirongia, Te Kūiti and Waikato."
Mac won the North Island open men's skeet handicap in Rotorua as a C grader.
Having shot 95/100, his 10 point bonus on handicap bumped him up to a winning score.
At last year's North Island Secondary Schools Championship at Waikato Gun Club, the sharp shooting teenager placed third in the single rise and runner-up in the skeet championship.
He also had the honour of captaining the North Island against the South Island in the skeet competition.
His long term goal is to one day represent New Zealand at the Olympics.
Mac played an influential role in his father's double success at the national championships in Christchurch
"There was no way Dad was going to compete until I mentioned that this could be your last chance for national glory as it won't be long before you are promoted to A grade."
The rest is now history — Livingstone senior showed the same skill, grit and determination to win the B grade high gun and single barrel title as that which saw him capped 23 times propping the Waikato rugby scrum from 1980-82.
His national clay target scores make impressive reading — single barrel 47/50, points score 75/75, 143/150, high gun 418/450.
