Mayors, police chiefs and prosecutors are lobbying for legislation requiring semiautomatic handguns made and sold in New York to "microstamp'' unique identifying information on spent bullet casings.
Microstamping leaves the identification marks when a shot is fired. Bloomberg says it would add about $12 to the $450 average gun price.
The National Shooting Sports Foundation says the technology is flawed, easily thwarted by criminals, and adds to legal owners' costs.
The Senate plans to vote on the measure Tuesday. The Assembly has approved a similar bill, which would take effect in 2012.