"The criminals won't go to purchase the guns because there will be a background check," Durbin said. "We'll stop them from the original purchase. You missed that point completely. And I think it's basic."
LaPierre responded that it was Durbin who failed to understand, adding as Leahy banged his gavel for order that "if you are not prosecuting them, you are not even stopping them."
He and other opponents of more gun control also depicted extreme scenarios of Americans under threat in their homes and at schools to make the case for access to semi-automatic weapons and high-capacity magazines.
"We all know that homicidal maniacs, criminals and the insane don't abide by the law," LaPierre said.
Another witness, Gayle Trotter of the Independent Women's Forum, repeatedly described scenes of women at home with their children needing weapons that would be banned under Feinstein's proposal to fight off bigger, stronger male attackers.
"An assault weapon in the hands of a young woman defending her babies in her home becomes a defense weapon and the peace of mind that a woman has as she's facing three, four, five violent attackers, intruders in her home with her children screaming in the background, the peace of mind that she has knowing that she has a scary looking gun gives her more courage when she's fighting hard and violent criminals," Trotter said. "If we ban these types of assault weapons, you are putting women at a great disadvantage."
Other witnesses and senators who support tougher regulations countered that the constitutional right to bear arms can be limited, for example, by the existing ban on private citizens possessing grenade launchers and other military weaponry.
"I think most people believe that, sure, we could have guards at schools," Feinstein said, making a reference to the Columbine, Colorado, school massacre in 1999 in which two students killed 13 people before shooting themselves. "I'm well aware that at Columbine there was a deputy sheriff who was armed who actually took a shot but couldn't hit the shooter there. The question comes, what do you do about the malls then? What do you do about our movie theaters? What do you do about businesses. We can't have a totally armed society."
The police chief of Baltimore County in Maryland, James Johnson, endorsed what he called the holistic approach urged by Obama to create a system that reduces access to guns for people who shouldn't have them.
"The best way to stop a bad guy from getting a gun in the first place is a good background check," said Johnson, the chairman of the National Law Enforcement Partnership to Prevent Gun Violence.
However, Denver University law professor David Kopel said the Supreme Court made clear in a Washington, D.C., case that gun controls could not include weapons used commonly by law-abiding citizens, such as the top-selling AR-15 semi-automatic rifle that Feinstein's legislation would ban.
The hearing showed agreement in concept on some issues, such as strengthening mental health screening. In general, though, it appeared to do little to create common ground on the issue.
Leahy said he hopes the committee will begin considering legislation next month.
The NRA's membership has spiked by 500,000 people since the Newtown shooting, bringing its number to more than 4.5 million, the group said Wednesday.
In the meantime, Kelly and Giffords have launched Americans for Responsible Solutions to push for gun control.
On Tuesday, Kelly said that despite the Tucson, Arizona, shooting that wounded his wife and killed six others, he and Giffords still support the Second Amendment, which guarantees Americans the right to possess firearms.
"But we really need to do something about the safety of our kids and our communities. It's gotten really out of hand," he said.
After Wednesday's hearing, Kelly made a point of approaching LaPierre to shake his hand as media cameras recorded the moment.