Former US representative Gabrielle Giffords, who was shot in the head in 2011, has appealed directly to Congress for tougher gun controls, saying: "Too many children are dying."
Ms Giffords, who suffered significant injuries in the mass shooting and still struggles with language, was speaking as a surprise witness in front of the Senate Judiciary Committee.
Supported by her husband, astronaut Mark Kelly, Ms Giffords said: "Speaking is difficult. But I need to say something important.
"Be bold, be courageous, Americans are counting on you."
Ms Giffords and her husband, who are both gun owners, have formed a political action committee to back politicians who support tighter gun restrictions.
Their Americans For Responsible Solutions group aims to counter the influence of America's powerful gun lobby, the National Rifle Association.
Mr Kelly described to the panel how the man who shot his wife fired 33 bullets in 15 seconds and was stopped only when he paused to reload.
He said the handgun would not have been illegal under a federal assault weapons ban that lapsed more than seven years ago, but the magazine that held more than 30 bullets would have been prohibited.
"We are simply two reasonable Americans who have said 'Enough'," Mr Kelly said. He added that the nation was "not taking responsibility for the gun rights our founding fathers have conferred on us".
The NRA also testified in front of the committee in the first gun control hearing since 20 children were shot dead in Connecticut by 21-year-old Adam Lanza.
NRA executive vice president Wayne LaPierre said gun control measures had failed in the past "and will fail again in the future".
He instead expressed support for better enforcement of existing laws, stronger school security and to better the government's ability to keep guns from mentally unstable people.
He said: "Law-abiding gun owners will not accept blame for the acts of deranged criminals."
Mr LaPierre's statement had a milder tone than recent NRA remarks.
These included a television ad that called Barack Obama an "elitist hypocrite" for voicing doubts about the NRA proposal of armed guards in every school in the country while his own children were protected at their school.
Mr Obama this month proposed a package that includes banning military-style assault weapons, requiring background checks on all firearms purchases and limiting ammunition magazines to 10 rounds.
The US has the world's highest rate of gun ownership, and gun sales have jumped since the Newtown shooting as some fear that the government will take their guns away.
The Constitution guarantees the right to bear arms, but some argue that the country's founding fathers more than two centuries ago could not have foreseen the speed and power of today's weapons.
Even if gun control proposals make their way through a Congress that is already busy with fiscal issues, some law enforcement authorities at the local level have already threatened not to enforce them.
The chairman of the panel, Democratic Senator Patrick Leahy, said closing loopholes in the background check system for gun purchasers will not threaten firearms owners' Second Amendment rights to own a gun and is a matter of common sense.
"The Second Amendment is secure and will remain secure and protected," he insisted.