Johnny Salafia, 38, was gunned down moments after answering the door of his Kings Point home on the NSW South Coast in June 2013, allegedly after chatter that a crew of Rebels bikies were going to "fix" him.

One bullet was found lodged in the former Rebel's buttocks and another was removed from his spine, ballistics expert Lucas van der Walt told the NSW Supreme Court on Thursday.

All up, five bullets - including one through the victim's head - were fired through the home's front screen door, Mr van der Walt said.

Two broke up as they hit the screen door.

But the expert was unable to say if the bullets all came from the same weapon, or exactly which firearm model fired them.

"They display insufficient detail to show ... whether they were discharged from one firearm," he said.

"You need the cartridge to be sure (about which gun model was used)."

The court heard the bullets most likely came from either a .38-calibre or a .357-calibre revolver, both of which retain spent cartridges.

A .38-calibre weapon was used by Robert John Stewart McCloskey to gun down the ex-bikie, according to prosecutors.

McCloskey, 45, has pleaded not guilty to murder.

While admitting to going to the Salafia home the night of the killing, McCloskey says he stayed in the car, unaware of the murder plot until after others fired shots.

Recordings of McCloskey admitting to shooting Mr Salafia were untruthful boasts, his lawyer has told Justice David Davies.

The Crown, in an opening address on Monday, said a witness had heard a senior Rebels bikie identity say "Robbie and his crew are coming down to fix Johnny".

The judge-alone trial resumes on Friday.

Australian Associated Press