Where there are lots of legal guns, there are lots of illegal guns. And more guns = more gun deaths and violence.
Here's a study that I found quickly:
"Between 2017 and 2021, ATF data shows that 99% of firearms traced as part of criminal investigations (“crime guns”) were purchased at a gun dealer, pawn shop, or from the manufacturer, with about 70% of crime guns coming from a licensed dealer.
However, ATF data shows that 58% of crime guns are possessed by someone other than the person that purchased the gun. In Detroit, 61% of recovered
guns were possessed by an individual who did not purchase the gun between 2017 and 2021.
Based on the data showing that many individuals arrested for gun crimes did not purchase the guns themselves, it appears that many of the guns used in crimes are obtained through “straw purchases,” where an individual has another person buy a gun on their behalf.
While stolen guns are also often used to commit crimes, the number of stolen guns appears to be far less than the number obtained through straw purchases and/or undocumented private sales. Even if a gun is purchased legally from a licensed dealer, it can change hands multiple times through private sales without any record. The majority of individuals who obtain a gun used to commit a crime purchase the guns from an unlicensed supplier who is not required to conduct a background check. This includes some online suppliers, individuals at gun shows, or many private sales. In a survey of individuals who were incarcerated for a gun crime, about half reported that they purchased the weapon from an unlicensed supplier.5 In contrast, only about 13% reported that they purchased a gun from a federally licensed dealer.
detroitmi.gov