and i agree with you there farmers would be the only exemption I could think of but they aren't the issue, most farmers i know (which isnt many I admit) wouldn't own a weapon capable of Christchurch and generally respect the damage they can do.
Even if you shoot for fun the gun range should own and store the weapons with rigorous security in place checked regularly by the police.
I was mainly referring to those that have them for "fun". a couple of my mates have firearms and they live in the city absolutely no reason for them. They feel like big men - even more so when they get on the drink its an accident waiting to happen
I can just imagine what one of them would do if say his wife and kid were killed by a drunk driver or something similar
Either way if it happens that banning guns saves just one of these massacres in the next 50 years well its worth it