The Independent Police Conduct Authority has found the shooting of a man at a Rangitikei campground in 2018 was justified.
The man was camping at Vinegar Hill with his partner and seven-year-old son when police were called after he began threatening his partner with a sawn-off rifle.
Other campers called the police who arrived at the campground while the Armed Offenders Squad (AOS) was still 60km away.
The IPCA report said the officers planned to observe the situation from a concealed location until the AOS arrived but armed themselves incase the situation escalated.
It said when confronted by police the man sped into the campground where he held the firearm at the head of an owner of a campervan, ordering him to drive towards the police.
The man then aimed his gun at an officer and then the dog handler.
The report said the officer who fired the shot believed the man posed a serious threat of death or grievous bodily harm to the officers.
Police then deployed the dog to help restrain the man "who continued to struggle violently" while three officers tried to handcuff him.
One of the officers said: "I couldn't believe how much he kept fighting. In my career I've had a few tussles with some meth-driven people and they're just on another planet."
"I just put it down that this guys's absolutely pinging on meth so pain's not an issue," the officer said.
Once he was restrained the police gave the man first aid for two dog bites and a gunshot wound before he was taken to hospital.
The findings show the use of force was reasonable in the circumstances and the officer was justified in firing and in deploying the dog.
Police Central District Commander Chris De Wattignar said the actions of the officer were in direct response to the life-threatening behaviour of the offender.
"The officer was confronted by a violent individual and was put in a situation where they had no option but to use their firearm.
This is the last step which any officer wants to take, however they responded appropriately to the situation."
The man later pleaded guilty to multiple charges in relation to the day and a custodial sentence was imposed.