A deadly group plot for revenge was conjured up days after a dispute about tattoos led to a man being bashed, a jury has heard.

Craig Anderson was fixing pushbikes in the front yard of his western Sydney home when he was executed on the evening of May 27, 2019.

The alleged shooter Jim Dastan is accused of planning the murder after his brother Josh was beaten up at Mr Anderson's Doonside home two days earlier.

A NSW Supreme Court jury heard Dastan gathered together a gang of four other men, including Sean Fairweather, and sought an inconspicuous car, ammunition and a Glock 9mm pistol to carry out the attack.

"The purpose of the gun was to get retribution for what had happened to Josh Dastan," prosecutor Philip Hogan said on Monday.

Mr Anderson took "ice" and sold the illicit drug from his Doonside home, jurors heard.

Visiting the house on May 25, Josh got into an argument with some brothers there regarding a postcode tattoo. The brothers allegedly called for backup with Josh then being attacked.

Dastan was livid when he heard that his brother "got jumped," the jury was told.

"I'm frothing. I'm gonna explode. I'm f***ing burningggg," he wrote by text message.

Arriving at the Doonside home on May 27, Dastan allegedly yelled out, "Ando, what happened to my brother?" before shooting Mr Anderson in the back, chest, leg and arm.

Two bullets pierced his lung and heart.

"Police and ambulances came but Craig Anderson was dead," said Mr Hogan.

Both Dastan and Fairweather have been charged with murder and participating in a criminal group.

The Crown alleges while Fairweather did not fire the fatal shot, he agreed to the plan to gun down and kill Mr Anderson.

His alleged role in the joint criminal enterprise was sourcing the firearm, waiting near Mr Anderson's house as a "plan B", and then taking the gun away after the shooting.

Fairweather also faces an additional two counts of possessing the pistol and defacing it by scratching the serial number off.

The pair have pleaded not guilty to all charges.

Dastan's barrister Jennifer Ellis said her client was an "innocent man" who denied there was any plan to kill Mr Anderson, that he visited the Doonside premises for revenge, or that he fired the killing shot.

She pointed out there was no gunshot residue found on his hands by police and questioned the credibility of two key crown witnesses who claimed Dastan was guilty of murder.

"These witnesses who accuse Jim Dastan of shooting Craig Anderson were drug addicts," she told the jury.

Fairweather's barrister Wayne Flynn called the murder "a serious matter, a sad matter", but urged jurors to consider the different sides to the story before handing down their verdict.

"There's a lot of water to flow under the bridge," he said.

The trial continues.