"It's strictly by coincidence that this has transpired. She jumped over her own fence into someone else's backyard which looked suspicious for the person who was in that house."
Police promptly found the woman in the Bader suburb but the package was missing.
"A subsequent search of the area found that rifle. She had tried to stash it behind a garage."
Cherry said the gun was a legitimate firearm which police traced back to the initial owner.
"But we're just working through how it came into this young lady's hands."
The gun was initially legally registered but had "since changed hands".
"It was potentially going to be used for organised crime purposes and it's a major coup that we were able to recover this and get it off the streets."
Cherry said the woman was not known to police.
He confirmed the gun was not the same AR-15 assault rifle lost from Hamilton by New Zealand Couriers in November.
That gun was being couriered to Wellington for repairs but never arrived.
The woman was due to appear in the Hamilton District Court today.