On his 27th birthday, Robert Jade Bell organised to go out with his mother and commit armed robbery.
Bell lured a 16-year-old and his teenage friends to a house in Brisbane's southwest in August 2021 by telling them he wanted to buy a car.
Instead of meeting Bell, they were confronted by his gun-toting mum.
Bell came up with a plan after seeing the teen's car ad, the District Court heard on Friday.
He asked the 16-year-old to meet him at a house before arranging for his mum and another co-offender to go with him to the Forest Lake home.
After the teen arrived with friends - aged 18 and 19 - at night, a co-offender led them to a room and Bell's mother walked in threatening them with a rifle.
Car keys, mobile phones and property were stolen.
The mother and co-offender told the teens they "knew exactly where they lived" if they intended going to police, before ordering them to leave.
Bell - who was at the house but not in the room or armed during the robbery - then drove the stolen car to his home.
"This was well planned but ... cowardly offending," crown prosecutor Farook Anoozer said.
"He committed the offence on his 27th birthday.
"Everything was planned by him but he used others ... (including) his mother."
It was similar to offences Bell and his mother had committed in 2019, Mr Anoozer said.
"In the sense that his mother was involved as the principal, there was violence in that offending, it was again about a car," he said.
Bell's mother received a head sentence of five years in jail in May, the court heard.
"It seems to me you have been greatly influenced by your mother," Judge Ken Barlow told Bell.
Bell, 27, intended to move away from Brisbane - and his mum - as soon as he was out of jail, defence barrister Emily Lewesy said.
"He recognises that they are not good for one another," she said.
Judge Barlow acknowledged the mother had a "greater involvement" but said Bell had organised the armed robbery.
"It must have been extremely frightening for those young people," he said.
Bell had been exposed to domestic violence and turned to drugs by the age of 13, the court heard.
By 2019 Bell was using drugs "full-time" to cope with significant mental health issues and personal and family tragedies, Ms Lewesy said.
Asked if he had anything to say before sentencing, Bell said: "I just want to say I am truly sorry for what I have done.
"I have only been getting into trouble the last couple of years. I have sobered up - going to jail has opened up my eyes."
He pleaded guilty to one count of armed robbery in company and was sentenced to three-and-a-half years in jail.
He is eligible for parole in September, with 312 days in pre-sentence custody considered time served.
