Gilmour pleaded not guilty and opted for a trial by jury in the Whangarei District Court.
But he admitted all the charges before the jury was empanelled.
A police summary of facts stated Nicholson and Gilmour hatched a plan to carry out the home invasion to frighten the victim as retribution for past perceived grievances.
In the early hours of August 15 last year, both men gained entry to the victim's house and struck him on the head with fists after putting bedcovers over him.
They said they had a gun and a hard-pointed item was pushed against the man's right ear, causing him pain. He struggled to breathe and managed to get his mouth and nose out of the bedcovers to get some air.
Gilmour bound the man's ankles with duct tape.
In court this week, Crown lawyer Nicole Dore said the attack was planned and carried out by two people, the victim was vulnerable, and violence was inflicted on him.
Restorative justice was declined by the victim, she said.
Defence lawyer John Watson said Gilmour did not make threats to kill and although he owned a pistol, it was never used in the commission of the offence.
Judge Keith de Ridder said it was clearly a planned and premeditated attack on a vulnerable man and threats were also made against his family.
He sentenced Gilmour to three years and two months in prison.
