Te Moananui was given CPR before St John Ambulance staff took him away on a stretcher. He died soon after in Thames Hospital.
"The two AOS officers were justified in shooting Mr Te Moananui. At the time the officers fired, Mr Te Moananui was pointing his rifle at them and they feared for their lives. The death of Mr Te Moananui was a tragedy but one that was unavoidable in the circumstances," authority chair, Judge Sir David Carruthers said.
The 33-year-old had battled mental health issues for several years.
The IPCA found the deployment of the armed offenders squad to Te Moananui's address and his sister's address in Thames was "timely and appropriate".
The AOS was cordoning off the sister's address when Te Moananui confronted them with a firearm.
That left police with no other tactical options.
Waikato Police district commander Bruce Bird accepted the findings of the report.
The use of pepper spray was not appropriate because Te Moananui was carrying a loaded, raised firearm and kept walking towards the officers and its use would require officers to get closer to him.
"This was a tragic situation for Mr Te Moananui and his family and a stressful time for everyone involved," Bird said.
"Police were confronted with a very difficult situation.
"The officers did not want to shoot Mr Te Moananui but, given the risk he posed, they were left with no other option," he said.
"Sadly, the incident ended with the loss of his life and we extend our sympathies to his family."
