A girl who cried with joy at receiving an AR-15 for her 13th birthday has penned an angry letter to the Prime Minister. 

Waikato local Maddy Millen-Turner loves going shooting on the weekends and has competed in gun competitions under her dad's gun licence. She was heartbroken when the Government banned high-power semi-automatic weapons after 51 people were shot dead in two mosques in Christchurch. 

She felt so strongly about the issue, she wrote a letter to Jacinda Ardern. Maddy's father Matt has supplied the "unscripted and uncoached" letter to the country's major news outlets. 

"My favourite birthday was my 13th because my dad surprised me with a AR-15 semi-automatic rifle," Maddy wrote. "This was the best day of my life, when he turned around and said to me 'this is yours now, happy birthday'. I couldn't control myself, I bursted [sic] out into tears of joy and couldn't thank him enough."

Maddy began to spend her weekends at gun ranges to work on her aim, but that all came to an end after March 15. 

"One day [dad] came up to me and said 'I have to tell you something important and serious'. I was happy and anxious at the same time, but I didn't expect this to come out of his mouth. 'From the Christchurch shooting incident, Jacinda has decided to take away all semi-automatics and any gun that can hold over 10 bullets. That means your rifle and mine have to go'.

"I started to cry and get frustrated of why she would do this because there are other guns out there that can still do the same thing and gangs would never hand them in anyway, I haven't even had this gun for a year and it's going to get crushed and not seen again."

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On September 14, Maddy and her dad went to hand in their guns at a firearm collection event at Waihi Rugby Athletic Club, an emotional day for them both.

"I lost it again and started to cry and leant into my dad for a hug. When we were at the desk going through the parts and guns I was fine but still very sad, but mine was the last one to get assessed and of course I cried again."

She's glad the buyback scheme gives them the money to buy more guns for deer staking and pistols for shooting competitions, but says she "doesn't know how long that will last".

"I am speaking on behalf of New Zealander shooters who do this as their hobby," Maddie wrote, directly addressing Ardern.

"I hope you get this and have a long hard think about what you have done to poor little girls and boys with hopes and dreams that have been crushed by you. Why couldn't you just change the gun laws and make them harder but not impossible, but you have just gone too far and banned them instead. Thank [sic] about that!"

"I, as her father, am incredibly proud of her bravery in expressing how she feels," Millen-Turner wrote as an aside to his daughter's letter. "She will become an outstanding young lady."

He blames the Christchurch terror attack on "police failings". 

In response to Maddie's letter, Ardern told Radio New Zealand the Government has purposefully not banned all guns because some Kiwis have legitimate reasons for owning firearms.

"The question we had to ask ourselves is 'do you require a gun that can have 20- or 30-round magazines attached to them... are they necessary to undertake hunting, for instance, and the answer for us was no."