A Johns Hopkins University study says yes - the 2007 repeal of the Show-Me State's "permit-to-purchase law" led to dozens more murders each year.
The law required buyers to apply for a permit through their local sheriff's office.
"Any handgun that was changing hands, you had to have a permit to purchase a gun, now, were there individuals selling guns without that? I'm sure there were," said Bob Cirtin, who teaches criminal justice courses at Evangel University in Springfield.
So what changed?
"Selling from individual to another individual, the permitting process does not apply," Cirtin said.
At American Gold Mine in St. Joseph, there is still a background check process - it's a phone call to the FBI.
"They fill out a form called a 4473 that has all the pertinent information: address, date of birth and several questions they have to answer," store manager Joan Bennett explains. "There's a division of the FBI that runs the person's name and information and will either proceed them immediately and they can purchase the gun and take it home that day. They can delay the process three days if they need to research it further."
At Gunsmoke in Springfield, sellers say buying through a dealer and going through the background check actually protects the purchaser.
"You know that everything's been run through the police department, so nothing's stolen, you know you're not buying a stolen gun," said store manager Brandon Reynolds.
Regardless of the research, not everyone agrees the results are directly related.
"Bad guys, the criminals, they're not going to obey the laws anyway. They don't care," Cirtin said.
Reynolds says it was a needless check:
"Basically [it was just an old Jim Crowe law] that was put in place in the 1920s to keep minorities from buying guns," he said.
According to the National Rifle Association, in the state of Missouri you are not required to register any of your firearms, nor are you required to have a license to own them.