But Wayne LaPierre, executive vice president and chief executive officer of the National Rifle Association, told the Senate Judiciary Committee, "Law-abiding gun owners will not accept responsibility" for the massacres that plague the United States.
The hearing was prompted by the mass shooting at Sandy Hook Elementary School in Newtown, Conn., Dec. 14 in which 20 schoolchildren and six adults were killed by a gunman who used his mother's legally registered weapons, including an assault rifle with high-capacity magazine.
LaPierre said schools need to be made more secure.
"It's time to throw an immediate blanket of security around our children," said LaPierre, who had to endure sometimes testy Democratic questioning during the hearing.
Giffords, an Arizona Democrat, was the target of multiple death threats after voting for healthcare reform in the House. She was seriously wounded Jan. 8, 2011, at a public event outside a supermarket near Tucson when a gunman shot her in the head, killed six others including a federal judge and a child, and wounded 13. She resigned her congressional seat last year to concentrate on her recovery.
The gunman, now serving multiple life terms, did not appear to have political connections.
The judiciary committee is considering curbs on assault weapons, limiting magazine size and expanding background checks for gun sales.
In a halting voice that grew firm when she was making her main points, Giffords told the panel, "This is an important conversation for our children, for our communities, for Democrats and Republicans. Speaking is difficult. But I need to say something important.
"Too many children are dying," she said, reading from a short statement. "Too many children. We must do something. It will be hard but the time is now. You must act. Be bold, be courageous, Americans are counting on you."
Giffords' husband, former astronaut Mark Kelly, told the panel, "Gabby's gift for speech is a distant memory, she struggles to walk and she is partially blind."
But he said, "We aren't here as victims, but as fellow Americans. ... We're both gun owners and we take that right and the responsibilities that come with it seriously. ... We are two reasonable Americans who have said enough is enough."
Kelly, a retired Navy captain, said the Tucson gunman emptied a 33-round magazine, and a 9-year-old girl was killed with the 13th round. He said the girl, Christina Taylor Green, would be alive today if the Jared Loughner's magazine was limited to 10 rounds or less.
Loughner never was reported to mental authorities and Arizona had data on more than 130,000 of the mentally ill never added into the background check system.
Kelly recommended several things: fixing background checks, closing the gun show loophole, removing the restrictions on federal research of gun violence and having "a conversation about the lethality of firearms we permit to be sold in this country."
LaPierre told the committee he was representing 4.5 million NRA members and the millions more who support gun rights.
"We join the nation in sorrow over the tragedy that occurred in Newtown, Conn.," he said. "We need to enforce the thousands of gun laws that are already on the books. ... Unfortunately we have seen a collapse of the prosecution of federal gun laws" during the Obama administration.
"Proposing more gun laws while failing to enforce the ones we already have is not a serious solution," LaPierre said.
The NRA executive said government should also reform mental health laws, but the federal assault weapons ban that expired in 2004 "had no impact on preventing crime." He said a U.S. Justice Department study did not find it effective.
Under questioning, he refused to endorse background checks in gun deals between private sellers and collectors.
The atmosphere became testy as Sen. Richard Durbin, D-Ill., questioned LaPierre.
Durbin said NRA members in his state come up to him and say, "Senator you just don't get the Second Amendment ... . We need the firepower and the ability to protect ourselves from our government, from the police if they knock on our doors."
LaPierre refused to address those comments, instead saying people all over the country fear "being abandoned by their government" during weather disasters and riots.
A member of the committee, Sen. Lindsey Graham, R-S.C., said he had an assault rifle at home, and cited the case of a Georgia woman who fired six rounds from a pistol at a violent intruder. Hit five times, the intruder was "still able to get up and drive away. ... I think the best way to interrupt a shooter ... is not to deny that woman" a 15-round magazine, he said.
"There can be a situation where a mother runs out of bullets because of something we do here," Graham warned.
James Johnson, chief of police for Baltimore County, Md., told the panel: "Like assault weapons, high capacity magazines are not used by hunters. They do not belong in our homes." He said the questions put to Durbin by NRA members were "scary, creepy and just not based on logic."
Gayle Trotter of the Independent Women's Forum said, "Guns make women safer." She said if Congress bans assault weapons, "You are putting women at a great disadvantage."
There were signs enacting new gun restrictions will be difficult. Before the testimony began, the committee's ranking member, Sen. Chuck Grassley, R-Iowa, said Congress should not use the Newtown school massacre as an excuse to enact new gun laws.
He said President Obama's actions to restrict guns was rightly generating fear of a "tyrannical federal government."
"Banning guns based on their appearance doesn't make sense," Grassley said "I also question bans on guns with large-magazine capacities."
Exploding whale video goes viral on Internet
Reindeer recovered after escaping from Santa during lighting ceremony