The parents of a boy killed in the Sandy Hook school massacre in 2012 have taken Bernie Sanders to task after he criticized a lawsuit they and the parents of other victims filed against gun manufacturer Remington.

In a March 6 debate with Hillary Clinton in Flint, Michigan, host Anderson Cooper raised the lawsuit, which he said might be thrown out due to Sanders-backed legislation that made gun manufacturers immune from lawsuits.

Sanders said that as he understood it the 'point of this lawsuit' was to make manufacturers liable for whatever use their customers find for their guns. 'What you're really talking about is ending gun manufacturing in America,' he said, 'I don't agree with that.'

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Suing: Mark and Jackie Barden (pictured) slammed Bernie Sanders after he said the lawsuit they and other parents of Sandy Hook victims made against Remington intended to 'end gun manufacturing in America'

Victim: Daniel Barden (left) was only seven when he was shot dead with a Remington Bushmaster AR-15 (right). The lawsuit focuses on this specific gun, which the Bardens say should not have been sold to civilians

But writing in The Washington Post Sunday, Mark and Jackie Barden, whose seven-year-old son Daniel was killed in the massacre and who comprise one of ten families suing Remington, said Sanders's remarks were 'simplistic and wrong.'

'This case is about a particular weapon, Remington's Bushmaster AR-15, and its sale to a particular market: civilians,' they wrote.

'It is not about handguns or hunting rifles, and the success of our lawsuit would not mean the end of firearm manufacturing in this country, as Sanders warned.'

The couple continued: 'We have never suggested that Remington should be held liable simply for manufacturing the AR-15,' but instead object to the company's 'calculated choice' to sell the weapon to the public while emphasizing its 'military and assaultive capacities.'

They went on to describe advertisements for the AR-15 that show the gun being wielded by SWAT teams and soldiers - people, they say, who genuinely do need strong firepower - and which use the tag line 'Consider your man card reissued.'

The advertisements promise 'power and glory' for those who use the weapon, the Bardens say, but that it does not belong outside the field of combat - and certainly not in the school in which their child died.

'The last thing Daniel's tender little body would have felt were bullets expelled from that AR-15 traveling at greater than 3,000 feet per second - a speed designed to pierce body armor in the war zones of Fallujah,' they wrote.

Distraught: These shots from the time of the Sandy Hook shootings show the pain felt by the parents of the children who attended the school. Ten families, including the Bardens, filed the suit against Remington

Tragic: The tragic deaths sent a shockwave through the US, but the Bardens' lawsuit may be held back by a bill voted for by Sanders that protects gun manufacturers from victims of crimes that use their guns

'Sanders has spent decades tirelessly advocating for greater corporate responsibility,' the couple continued, 'which is why we cannot fathom his support of companies that recklessly market and profit from the sale of combat weapons to civilians and then shrug their shoulders when the next tragedy occurs, leaving ordinary families and communities to pick up the pieces.

'Remington and the other defendants' choices allowed an elementary school to be transformed into a battlefield. Our case seeks nothing more than fair accountability for those choices.'

In the March 6 debate, Cooper asked Sanders what he would say to families like the Bardens whose lawsuit might be thrown out due to the 2005 Protection of Lawful Commerce in Arms Act (PLCAA), which stops victims of criminal gun violence taking action against manufacturers.

In his reply, Sanders - who voted in favor of the PLCAA - couched his remarks by saying he didn't fully understand the suit.

'Well, this is what I say, if I understand it - and correct me if I'm wrong,' he said. 'If you go to a gun store and you legally purchase a gun, and then three days later, if you go out and start killing people, is the point of this lawsuit to hold the gun shop owner or the manufacturer of that gun liable?'

He said that if so he disagreed with it - although he was in favor of prosecuting those who sell guns to criminals.

'But if they are selling a product to a person who buys it legally, what you're really talking about is ending gun manufacturing in America. I don't agree with that.'

'Simplistic': Sanders's remarks, in which he said he believed the suit's message was to stop gun production in the US, were decried as 'wrong and simplistic' by the Bardens. He made them during a debate on March 6

Debate: The Democratic debate, held in Flint, Michigan, had Sanders saying, 'As I understand it... and maybe I'm wrong, what you're really talking about is people saying "Let's end gun manufacturing in America."'

Clinton disputed his remarks, saying that people 'were working on legal theories that they thought would force gun makers to do more to make guns safer and force sellers to be much more responsible.'

She also said that the National Rifle Association was behind the PLCAA because it worried that overly safe guns - with fingerprint technology or stronger safety locks - would not sell as much as more 'dangerous' variants.

'No other industry has absolute immunity,' she said.

The two argued on the topic, which concluded with Sanders saying, 'I was there in the Senate when we learned about [the Sandy Hook shooting]. It is almost unspeakable to talk about some lunatic walking into a - I mean; it is hard to even talk about it.

'We all feel that way. But it, as I understand it, Anderson, and maybe I'm wrong, what you're really talking about is people saying "Let's end gun manufacturing in America." That's the implications of that, and I don't agree with that.'

The Sandy Hook shooting occurred on December 14, 2012, when 20-year-old Adam Lanza walked into Sandy Hook Elementary School and fatally shot 20 children aged between six and seven years old, as well as six adult staff members and ultimately himself.