A great-nephew of backpacker murderer Ivan Milat has lost an appeal against his sentence for killing his friend with an axe.

But his accomplice has had his sentence reduced.

Matthew Milat and Cohen Klein appealed the severity of their sentences handed down in 2012 for murdering teenager David Auchterlonie in the Belanglo State Forest.

Milat, who was a teenager at the time, murdered David with an axe on his 17th birthday in the same forest used by his relative and serial killer Ivan Milat.

Milat was sentenced to at least 30 years, with a maximum term of 43, for the 2010 murder.

Klein was jailed for at least 22 years, with a maximum 32-year term.

In a judgment handed down by the Court of Criminal Appeal on Friday, Milat’s appeal was dismissed.

Klein’s appeal was allowed and his original sentence was quashed, with the court instead sentencing him to serve at least 20 years in jail with a maximum of 27.

He will be eligible for parole on November 21, 2030.

During an appeal hearing last year, deputy senior public defender John Stratton SC, representing Milat, submitted that the crime was heinous, but it was not in the worst class of murder.

Mr Stratton argued for a maximum 22-year jail term with a non-parole period of 15 years.

Klein’s barrister, Janet Manuell SC, said Milat was the dominant one who found the weapon, organised to bring the victim to the forest, delivered the fatal blow, and later bragged about it.

“The role of (Klein) was one of support and facilitation,” she told the appeal hearing.

The axe attack took place in the same NSW Southern Highlands forest where Ivan Milat murdered seven backpackers in the early 1990s.

David’s grandparents said they were dismayed with the reduction in Klein’s sentence.

“I am very disappointed because he did the crime and he should do the time,” Sandra Auchterlonie told reporters outside court.

“It’s not going to bring David back.

“David is gone. He had a life ahead of him and these people took it from him.”

Grandfather David Auchterlonie said Klein could have stopped Milat.

“He had three occasions he could have done that,” he said.

“Just another example of how the law is so far out of touch with the public.”