New Zealanders have begun handing in weapons in response to government appeals following the Christchurch massacre, but the gesture has put some squarely in the social media firing line.
John Hart, a farmer in the North Island district of Masterton, decided to give his semi-automatic rifle to police after Prime Minister Jacinda Ardern announced on Monday plans to tighten gun laws in light of the slaughter Friday of 50 Muslim worshippers.
She also encouraged owners to surrender unnecessary firearms after it emerged that the accused mosque attacker, Australia white nationalist Brenton Tarrant, had legally acquired the guns he used in the rampage.
Hart said it was an easy decision for him to hand in his semi-automatic and tweeted that "on the farm they are a useful tool in some circumstances, but my convenience doesn't outweigh the risk of misuse. We don't need these in our country".
The tweet drew a barrage of derogatory messages to his Facebook account -- most apparently from the US, where the pro-gun lobby is powerful and vociferous.
Hart deleted the messages but posted online: "A warm kia ora to all my new American Facebook friends."
"I'm not familiar with your local customs, but I assume 'Cuck' is a traditional greeting," he said of the insult, short for "cuckold', frequently used by far-right extremists.
Hart told AFP many of the messages made inaccurate references to his sexuality.
"It was very sudden. It started about the time the US east coast was waking up. There seemed to have been a rallying call," he said.
A more mild message, from Kaden Heaney asked: "What's the point of giving up yalls personal guns? Yall do realize what happens to societies that give up their guns right? Evil people will get their hands on guns, knives, bombs or whatever they want to kill no matter what the intentions of good people are. Who will protect you."
Christopher @offwhiteblogger said: "You did the right thing then; you clearly aren't responsible enough to own a firearm."
Police said they did not have data available on the number of weapons handed in since Friday.
But they issued a statement saying that "due to heightened security and the current environment, we would ask that people please call us first before attempting to surrender a firearm."
A person calling himself Blackstone tweeted: "this is one of the easiest decisions I have ever made. Have owned a firearm for 31 years ... Once I realised that, the only way I could go forward with a clear conscience was to hand it into the police for destruction."
Ardern has said that details of the government's proposed law changes on gun ownership will be announced by next week, but she indicated that gun buybacks and a ban on some semi-automatic rifles were under consideration.
"As the Cabinet, we were absolutely unified and very clear: the terror attack in Christchurch on Friday was the worst act of terrorism on our shores, it was in fact one of the worst globally in recent times, it has exposed a range of weaknesses in New Zealand's gun laws," she said.
New Zealand police, meanwhile, were investigating a suspicious fire at a gun club in the far north of the country, but were not immediately linking it to the current gun debate.
There had also been a fire at the same club a year ago.