Philadelphia's pension board voted unanimously Thursday to ask all gun manufacturers, distributors and retailers with whom it has invested city pension money to adopt a set of eight "Sandy Hook Principles" designed to reduce gun violence.

The board established procedures to track whether the companies are complying with the principles, and to dump its investments within 15 months if the companies fail to comply.

Between its direct investments and holdings in hedge funds that invest in gun makers, distributors and retailers, the city owns about $15 million in gun-related investments, about one-quarter of 1 percent of its total portfolio, according to a staff analysis.  Besides well-known gun makers like Smith & Wesson, the list extends to major retailers like Walmart.

Mayor Nutter proposed the pension board action last week as local and state officials around the country explored ways to use their financial clout to spur reforms in the gun industry, in response to the December shootings of 20 children and six adults at the Sandy Hook Elementary School in Newtown, CT.

The resolution offered by City Solicitor Shelley Smith at Thursday's pension board meeting referred to both the Sandy Hook massacre and "too many others who have lost their lives to gun violence before and since."

The eight principles, pared down and less specific than the 20 principles that Nutter proposed last week, include requests for the gun industry to:

--Support restrictions on firearms and ammunition sales intended to keep guns away from children, people with mental health issues, criminals and anyone else prohibited from gun possession by federal law.

--Conduct background checks on all gun and ammunition sales and transfers, and support creation of a system of universal background checks, run by the federal government.

--Re-evaluate any policies regarding sale, production or conversation of military-style assault weapons.