They were hidden at various places through his house, including in a wall cavity.
"The potential danger posed by the presence of these weapons, were they to find their way into the community, is obvious," Justice Fitzgerald said.
Cranch also had access to 2500 rounds of ammunition and several high-capacity magazines, and four grams of methamphetamine was found in his garage.
Cranch, whose firearms licence was revoked in 2006, claimed to have been merely storing the firearms at his North Shore property for other people and the judge said that there was "no suggestion" he had been intending to use them.
However, "he was in possession of the prohibited firearms for the better part of a year without advising the authorities, despite the obvious danger to the community in the event the firearms passed into the wrong hands", Justice Fitzgerald said.
After Cranch was sentenced, police appealed, arguing that a prison sentence would have been appropriate.
However, Justice Fitzgerald said that the sentencing judge, Judge Anna Fitzgibbon, "fell into error" because the prosecutor suggested a starting point which effectively endorsed a home detention sentence, and this had been in line with an earlier sentencing indication.
Cranch did not have any significant recent criminal offending, and had never been to prison. He had successfully served eight months of the nine months of home detention imposed.
"To allow the appeal and require Mr Cranch to surrender into custody now would accordingly be a very significant matter and no doubt a shock to him."
Justice Fitzgibbon said an appropriate sentence would have been 28 months in jail, above the two-year threshold where home detention is an option.
A law change after the Christchurch mosque shootings in 2019 saw most MSSAs classified as prohibited weapons and increased the maximum penalty for possessing them from three to five years in prison.
