"Glock was really the driving force behind police departments switching from revolvers to semi-automatic," Rand said. "They have been very successful at marketing to police departments."
Rand said gun buyers outside of law enforcement soon caught on to the Glock's popularity to mimic law enforcement gun trends.
Rand said the Glock 19 has been used in other mass killings, including the Virginia Tech shooting in April 2007. In that incident, Seung-Hui Cho used a Glock 19 and a Walther P22 rifle to kill 32 students and take his own life.
"They blazed the trail of popularity among law enforcement agencies to sell to the general public," Rand said. "They would say 'You want the same gun used by law enforcement.'"
Rand also said the materials and look of the gun, which other manufacturers have emulated, helped fuel sales.
"It was one of the first high tech-looking guns to utilize polymers and plastics, as opposed to all metal," she said.
Gun-control advocates are using the incident in their campaign to bring back the Federal Assault Weapons Ban, which was enacted in 1994 but expired in September 2004.
Sen. Frank Lautenberg, D-N.J., and Rep. Carolyn McCarthy, D-N.Y., announced Monday that they intend to introduce legislation to prohibit the manufacture and sale of high-capacity ammunition feeding devices, such as the Glock 19.
Paul Helmke, president of the Brady Campaign to Prevent Gun Violence, wrote in a statement: "If Congress had not allowed the 'Assault Weapons Ban' to expire in 2004, the shooter would only have been able to get off 10 rounds without reloading."
Loughner was allegedly able to fire at least 20 rounds from his 33-round clip, according to Helmke.