This was an amazing achievement for both shooters up against 110 competitors from New Zealand and overseas.
They followed up with shooting another round of 25 targets as part of the North Island team that defeated their South Island competitors.
After a week of blasting hundreds of clays into tiny pieces they were rewarded with selection in the New Zealand Junior Mackintosh Skeet team for the Australia/New Zealand Trans-Tasman Skeet Postal Challenge held on the final day of the nationals.
It was Gwillim's second year to wear the black blazer but a first for Clark.
"I am really happy with how it went. It was better than last year. Skeet and DTL are my specialities. I quite like doing both of them," Gwillim said.
"I started at Year 9 and thought I would give it a go. Ben Tuck has been very helpful in the DTL for the school team."
Tuck says both shooters have the right attitude and dedication to succeed.
"For Bay of Plenty to have two shooters at such a young age at Tauranga Boys' College shooting skeet like they are, well they are going to go somewhere all right."
Making the New Zealand team was the main goal for Clark who in June became the first New Zealander to win the Australian sub-junior title.
"I have solely dedicated myself to the skeet discipline. I find it is more of a mental challenge and it has helped me go through day-to-day life," Clark said.
"Clay target shooting has really helped me with overcoming things. Concentration is really important for clay target shooting because sometimes you can drop in and out and in an exam at school it is important to stay focused."
Next event on the schedule for Gwillim and Clark is the 2018 North Island Skeet Championships in Rotorua next month.
"I am not sure how we will go but it is an important event. It just depends on how well you shoot on the day to see where you get," Gwillim said.