Wheeler, who grew up in Bucks County, asked legislators to end an exemption in Pennsylvania law that lets someone buy a rifle in a private sale - say, online - without undergoing a background check.
"I think we all agree that expanding background checks will not eliminate all crime," she said, choking back tears. "The assault weapon that was used to kill my Ben, for example, was purchased legally, by the shooter's mother after a background check."
"But," she said, "if we are looking only to take steps that will stop all gun crimes, we set the bar for action too high. We know that background checks prevent convicted felons or mentally ill from buying guns."
The hearing before the House Judiciary Committee was billed as an informational session rather than a debate on a specific bill. But State Rep. Steve Santarsiero (D., Bucks) introduced legislation this year to expand background checks in the state to include purchases of long guns, including assault rifles, conducted in private sales.
Santarsiero said Wednesday that he had been unable to get a hearing on his bill in the committee. He said its chairman, Rep. Ron Marsico (R, Dauphin), had not committed to holding one.
Existing federal law requires licensed gun dealers to do background checks on buyers in any type of firearms purchase, but it does not cover gun shows. Pennsylvania law goes further, requiring anyone selling handguns to perform background checks - but it exempts sales of long guns.
Advocates for changing the law contend this exemption has allowed a proliferation of unregulated sales of long guns, especially on the Internet.
Santarsiero on Wednesday argued that changing the law to remove the exemption is "an appropriate place to begin."
He predicted that if the measure were to ever reach the floor of the Republican-controlled House, members would pass it - notwithstanding the legislature's traditional resistance to enacting gun limits.
John Hohenwarter of the National Rifle Association, whose group is against expanding the background-check system to include long guns, testified Wednesday that rifles and shotguns are involved in only about 4 percent of Pennsylvania homicides.
Wheeler, for her part, said she had been stunned by the rancor surrounding the debate on how best to strike a balance between respecting gun owners' rights and enacting commonsense regulations to ensure that guns are purchased and used responsibly.
But the Council Rock High School graduate has nonetheless taken a frontline role in that debate. In April, at President Obama's invitation, Wheeler delivered the president's weekly radio address, trying to rally support for the expanded federal background-checks bill crafted by Sens. Joe Manchin (D., W. Va.) and Pat Toomey (R., Pa.). The bill, fiercely opposed by the NRA and other gun-rights groups, did not garner enough votes to pass the Senate.
In Harrisburg, Wheeler said her son's death had stripped her of fear and had given her the courage to speak up.
"All this stems for the love I have for him," she said. "This is how I honor Ben and how I honor all victims of gun violence - by having the courage to find love, listen to one another, and make change happen."
Contact Angela Couloumbis at 717-787-5934 or firstname.lastname@example.org, or follow on Twitter @AngelasInk.
This article contains information from The Associated Press.