A gun buyback program that began last month in Connecticut’s biggest city has netted more than 500 weapons, including several dozen assault-style weapons. Bridgeport city officials said more than $150,000 has been donated in the form of cash and grocery store gift cards to buy back guns from people. The latest session of the program is Saturday, and Mayor Bill Finch said it will continue for as long as necessary. Police are offering up to $200 for a working handgun and $75 for rifles. Over six sessions, the public has turned in 539 weapons, with officials paying out $59,350 in return.