Alleged murderer sledges slain man in jail

A gunned-down environmental compliance officer thought he was "somebody bloody special", his alleged murderer Ian Turnbull said from behind bars.

The Sydney jury deciding the NSW farmer's case was on Thursday played snippets of telephone calls the 81-year-old sent and received while being held in custody in the months after the July 2014 shooting.

"He exacts his power over and above what the Native Vegetation Act is ... like he is somebody bloody special - or he was, anyway," Turnbull told a woman in a telephone recording aired in the NSW Supreme Court on Thursday.

Turnbull admits fatally shooting 51-year-old Glen Turner at Croppa Creek, near Moree in the state's north, but has pleaded not guilty to murder.

His lawyers have suggested the elderly farmer snapped under immense pressure from ongoing court proceedings.

On Thursday, jurors were also shown how to operate the pump-action rifle used to shoot Mr Turner.

Ballistics expert Matthew Bolton showed the jury how to load and fire the .22 calibre Belgian-made gun, as well as how to spit out spent cartridges.

A number of the dead man's relatives appeared to wipe away tears as the weapon was produced and held aloft for jurors to see.

Mr Bolton said ballistics tests confirmed that spent cartridges recovered from the shooting scene matched the alleged murder weapon.

The jury has been told that on July 29, 2014, the evening Turnbull killed Mr Turner, the farmer was working at a nearby property when he got word through one of his employees that the Office of Environment and Heritage officer was in town.

The pair had crossed paths before, as Mr Turner was involved in bringing several land-clearing prosecutions against members of the Turnbull family.

Crown Prosecutor Pat Barrett has told the jury that Turnbull drove to Talga Lane, where Mr Turner was with fellow environment officer Robert Strange, and parked his ute.

Then - armed with the rifle that he is said to have kept stashed behind a seat for shooting wild pigs and kangaroos - Turnbull stepped out of the vehicle, raised the weapon and without saying a word, shot Mr Turner in the neck.

The 51-year-old fell to his knees, stood up again, and was hit with a second shot to the chest.

The court has heard how, as the light faded that evening, Turnbull shot Mr Turner several times as Mr Strange pleaded with him to let them get help.

At last, Mr Barrett has said, Mr Turner made a desperate run for a line of trees a short distance away and was shot a final time.

Counsel for the accused, barrister Todd Alexis SC, has suggested that "ongoing and unrelenting" court proceedings exerted such immense pressure on the elderly farmer that he "lost self-control and snapped in the moment".