Criminals are far more likely to acquire guns from family and acquaintances than through theft, says a study.
"There are a number of myths about how criminals get their guns, such as most of them are stolen or come from dirty dealers. We did not find that to be the case," said Philip Cook, a professor at Duke University in Durham, US.
One study asked inmates of the Cook County Jail in Chicago how they obtained guns, while a second project analysed data that traced guns used in crimes.
The gun trace requests were submitted to the federal Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) by the Chicago Police Department from 2009 to 2013.
The researchers found that 60 percent of the respondents obtained guns through purchase or trade.
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Most offenders obtained guns from personal connections, not from gun stores or through theft.
Most of the guns were old (11 years old on average), and criminals held onto the guns only for a short time, frequently less than a year.
Chicago gun laws prohibit selling guns to people with criminal records, or those under 21 years of age.
"Dirty dealers", who deliberately violate the law and sell to buyers who cannot pass a background check, accounted for less than five percent of the guns sold to gang members.
More than 60 percent of the crime guns were initially purchased out of state.
Meanwhile, 15 percent of new crime guns confiscated from a man were first purchased by a woman, which suggests a straw purchase, the study noted.
The findings suggest that targeting by law enforcement of the intermediaries in the underground market, the straw purchasers and the traffickers helps reduce access to guns by some dangerous people, Cook said.
The findings will appear in a forthcoming issue of the Journal of Criminal Law and Criminology.
