Variation in guns laws from state to state may be complicating law enforcement efforts, especially in regions such as New England, where states are split between restrictive and largely hands-off approaches to gun ownership, according to some gun law specialists and gun control advocates.

Those looking to cut gun violence, however, should look beyond rifles, said Jack Levin, a criminology professor at Northeastern University and co-director of its Center on Violence and Conflict.

“The gun problem in this country has little to do with the prevalence of semiautomatics,” Levin said. “There are 15,000 single-victim murders in the United States every year, about two-thirds of which are committed with firearms. The overwhelming majority of these homicides are committed with handguns.”