Anthony Robert Moore (48) was sentenced to three years, four months' imprisonment before the High Court at Greymouth in October for unlawfully possessing a firearm and perverting the course of justice.
When the Court of Appeal sat in Dunedin last week, his counsel Marcus Zintl argued the sentence was excessive.
In a decision released yesterday Justice Forrie Miller - who heard the case with Justices Christine French and Graham Lang - said there was nothing that showed the prison term was disproportionately severe.
Indeed, he said, Moore was lucky to receive the credit he did for his guilty plea which came nine months after he was charged and in the face of a strong case against him.
Despite being denied a firearms licence, Moore had two weapons, including a sawn-off shotgun, and provided one to George Sean Warren who claimed he needed protection from a gang.
On October 22, driven by Corey Robert Towersey, Warren went to Hayley Jane Williams' home, angry about an indecent assault complaint she had made against him.
He shot her in the throat outside her home, killing her instantly, while her three children were at the address.
Moore and Towersey had agreed to suppress details of their involvement.
They discussed threatening other witnesses, destroyed their phones to avoid detection and told witnesses not to use text messages for fear of information emerging about their respective roles.
Despite that, Mr Zintl argued his client should have received a discount from his sentence
for remorse.
Moore wrote a letter of apology saying that he was a friend of the murdered woman and never had any untoward feelings for her, the court heard.
"Mr Moore did not know that the firearm would be used to kill the victim but he did know that it was loaded and it would be used to `deal with' gang members," Justice Miller said.
Mr Zintl also highlighted the fact no restorative-justice conference between the appellant and the victim's family had been explored.
That was no prerequisite to sentencing, the Court of Appeal ruled.
"We have not been pointed to anything, such as the attitude of the victim's family, that suggests any restorative justice process would have affected sentence," Justice Miller said.
Moore had a "significant though mostly low-level criminal history", he said, which included convictions for domestic assaults and unlawful possession of a firearm.
In June last year, Warren was jailed for life with a minimum non-parole period of 17 years.
Towersey was sentenced to four years, eight months' jail for manslaughter at sentencing last month.
