The antitrust investigation also comes as 30 cities and counties have filed lawsuits against gun manufacturers, wholesalers and retail dealers. Some cases are expected to soon reach the discovery phase, during which lawyers for the municipalities hope to uncover documents showing the gun industry was aware that its sales practices helped make it easy for criminals and juveniles to buy handguns. The suits against the gun makers charge them with failing to incorporate safety devices and negligently marketing their guns so that criminals can buy them.