A 48-year-old man is facing multiple charges after police found a weapons, cash and methamphetamine at a Te Atatu property on Friday.
Police were called to the address around 11am after reports of two men fighting with golf clubs.
However upon arrival they discovered drugs, and began a full search of the property.
They found four AR15 firearms, more than 400 rounds of ammunition, 2kg of methamphetamine and an estimated $2.5 million in cash.
"This was a significant find, and it's enormously pleasing to have these drugs and firearms off the street," says Det Snr Sgt Roger Small.
"The methamphetamine found has an estimated street value of $2 million and would have had a devastating impact on our community if it had made its way to users.
"And of course, methamphetamine not only adversely affects the users. It causes a huge amount of harm to the users' loved ones, as well as being a driver of numerous other crimes in our communities as a result of users trying to fund their habits."
The 48-year-old man is now in custody and is facing charges of unlawful possession of firearms, unlawful possession of ammunition, and possession of methamphetamine for supply.
He will appear in the Waitakere District Court today.
The AR15 rifle has been used in a number of mass shootings in the US, including by the Las Vegas killer Stephen Paddock and the gunman who shot up a Texas church last year, killing 26.