Dec. 20, 2012 -- Colin Goddard knows what it's like to be in a classroom when an armed man bursts through the door and starts randomly shooting people. Goddard was a student at Virginia Tech when a gunman shot him and killed 32 people in the deadliest mass shooting in U.S. history.
"It was the most terrifying nine minutes of my life," Goddard told Terry Moran of "Nightline" Wednesday. "One moment you're conjugating French verbs, the next you're shot."
Four of Seung-Hui Cho's bullets hit Goddard April 16, 2007. Three of the bullets are still in him and serve as a constant reminder in his work with the Brady Campaign to Prevent Gun Violence.
Goddard, 26, does more than lobby and appear in public-service announcements. He says he goes undercover to show how easy it is to buy guns without any background check. It's the subject of his documentary called "Living for 32," after the 32 people who died at Virginia Tech in Blacksburg.
"There is not one thing that will stop all shootings," Goddard said. " There's not one policy that will save us all, but a background check is something that will make it more difficult for dangerous people to get their hands on a gun."
In "Living for 32," Goddard says he was able to buy, for example, an Egyptian Maadi AK-47, a TEC-9 and a MAC-11 machine pistol at gun shows across the United States.
"I bought the same gun that was used to shoot me," he said. "I bought it all, all without a background check and it was all legal. My question is, 'Why is that legal?'"
Only licensed dealers are required by law to perform background checks on the people to whom they sell guns while private sellers can make gun-show sales with no background checks.
This is known as the "gun-show loophole" and Goddard has made it his mission to close it.
In one scene in the documentary, Goddard appears to able to buy the Maadi Egyptian for $660 and was told by the dealer "there's no tax and no paperwork."
The dealer requested to see Goddard's Ohio driver's license. When Goddard couldn't provide it, he is shown as still being able to purchase the gun by providing an Ohio address instead.
"I didn't think I was going to be able to do it at first," he said. "And then once I did it once, then twice, then three times. I was like, 'Wow, this is really easy.'
"Toward the end I wasn't even thinking about it. I tried to do it as quickly as I could, say as few words as I could."
Polls show that a majority of Americans favor closing the loophole.
Goddard says closing the loophole won't end all gun violence, but that the government can do better.
The Brady Campaign recently launched a YouTube series, "We Are Better than This," in the wake of last week's shooting at Sandy Hook Elementary School in Newtown, Conn. The videos feature celebrities and, perhaps more significantly, families of mass-shooting victims.
In the first three videos, Goddard appears, as do Lonnie and Sandy Phillips, whose daughter Jessica Redfield Ghawi, died in the Aurora, Colo., mass shooting in July.
"We are better than this," Goddard says in one of the videos. "We are better than a nation with mass shootings in our movie theaters and in our schools and on our streets."
It's a job Goddard was drawn to after he watched classmates around him shot to death at Virginia Tech. Weeks after the shooting, Goddard recalled the scene in an interview with ABC News.
"The shooter came inside and we were all on the ground not moving, not making a scene at all," he said in 2007.
"Just lying there, acting, playing dead. ... And we were just at his mercy. He could have done whatever he wanted to. He chose to go around the room in such a way that he killed all the other students in my class except for a few of us."
Goddard's journey to recovery began on that classroom floor and took him through rehab, psychological therapy and the search for answers. The difficult journey has led his becoming one of the country's top, young advocates in the fight to curb gun violence.
As the nation struggles to make sense of the Newtown shooting, Goddard knows what the surviving victims and their families are going through.
"It's the worst day of their life," he said. "It's chaotic, it's hopeless."
Goddard doesn't consider himself a victim but a survivor who is depending on people to come together on this issue and share in his youthful conviction.
"That's why I share my story," he said. "This is only going to be a period of my life. It's not going to be forever, but to the extent I can share my story and move the ball forward.
"Let's do it and save lives."