Matthew Kaplantzi will spend his 21^st birthday behind bars in a few weeks as he awaits sentencing over the November 2019 incident, which left a 16-year-old and a 17-year-old with wounds to their forearm and chest.

Documents tendered to Wollongong Local Court on Wednesday reveal the group of teens were outside a house in Windang on the evening of November 15 when Kaplantzi drove up in a grey BMW sedan.

He stopped the vehicle and one of the teens approached the driver's side window.

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Kaplantzi handed the teen a small bag of cocaine, which he took without giving Kaplantzi any payment.

Kaplantzi then drove home, picked up a small BB gun and returned to the Windang property about 20 minutes later.

The court heard he held the gun outside the window as he slowly drove past the house and fired more than 10 shots towards a group of three teens, who were still standing outside the home.

One of the teens was hit in the forearm, leaving him with a small puncture wound, while a second teen was hit in the right side of his chest, causing a small blood blister.

Meanwhile, pellets from the gun hit the back window of a car parked in the driveway, causing the window to shatter.

Further pellets were found in a glass panel at the front of the house and in the home's exterior cladding.

A neighbour contacted police immediately. Officers who were nearby raced to the scene and saw Kaplantzi's BMW as it turned into another street.

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They pulled the vehicle over and carried out a search, locating the BB gun under the front driver's seat.

They also discovered cocaine and $200 cash inside a bum bag owned by Kaplantzi.

Officers then went to the house and spoke with the victims, each of whom identified Kaplantzi as the shooter.

Kaplantzi was subsequently arrested and taken to Lake Illawarra Police Station where he was charged.

When interviewed, he admitted attending the house earlier that evening to supply one of the teens with cocaine, saying he had carried out the errand of behalf of a friend.

He admitted returning home to get the BB gun after the teen failed to pay him, however denied he had shot at the group intending to cause them any injuries..

He told police he had only wanted to cause damage to the vehicle parked in the driveway.

Kaplantzi was remanded in custody at the time.

He fronted court on Wednesday via video link from jail where he entered guilty pleas to one count each of firing a firearm at a dwelling with reckless disregard for the safety of others and using an unauthorised pistol.

Further charges of possessing a prohibited drug, unregistered firearm and ammunition will be taken into account when he faces sentencing at a later date.