For their part, the manufacturers argued that the lawsuits were a frivolous abuse of the courts to grind them down financially. They also pointed to voluntary measures, like the industry trade association’s distribution of safety locks to gun owners, as evidence of their concern about reducing accidents.

The Times reached out to a half-dozen gun makers for comment. Most did not respond or declined. But Timothy A. Bumann, a lawyer for Taurus International Manufacturing, reiterated some of the arguments made by gun executives in their depositions, saying Taurus is not a law enforcement agency and has no legal duty to do more to police its dealers and distributors. Nevertheless, he said, the company is “proactive in all the things it reasonably can do vis-à-vis the safe and lawful use of its product.”

Lawrence G. Keane, senior vice president of the National Shooting Sports Foundation, the industry’s trade association, said in an e-mail that the Bureau of Alcohol, Tobacco, Firearms and Explosives “does not want manufacturers to play Jr. G-man.” He also highlighted a number of ways the association had worked with the A.T.F. — including an education program to prevent people from illegally buying guns and transferring them to people barred from doing so that was more than a decade old — as evidence of the industry’s commitment.

The lawsuits were bolstered, however, by testimony from several former industry insiders. The most prominent was Robert Ricker, a former lawyer for the National Rifle Association and executive director of the American Shooting Sports Council, the main gun industry trade association before it was disbanded.

“Leaders in the industry have consistently resisted taking constructive voluntary action to prevent firearms from ending up in the illegal gun market and have sought to silence others within the industry who have advocated reform,” Mr. Ricker wrote in a 2003 affidavit on behalf of the City of San Diego.

Mr. Ricker detailed the backlash from the N.R.A. and trade groups against anyone who pressed for changes to industry practices. Because of his calls for reform, Mr. Ricker, who died of cancer in 2009, said he was forced to resign as the head of the trade group.

Another insider, Robert Hass, a former Smith & Wesson executive, testified that “the nature of the product demands that its distribution be handled in such a way as to minimize illegal and unintended use.” And yet, he said in an affidavit, “the industry’s position has consistently been to take no independent action to ensure responsible distribution practices.” When Smith & Wesson voluntarily adopted a set of safeguards, including requirements that its dealers limit multiple sales of firearms, it was ostracized and boycotted, forcing it to abandon the changes.