Mr. Contois, from the Sacramento-area community of Cameron Park, and his lawyer, Peter Hinton, contend that KEE Action Sports, the successor to National Paintball Supply, inherited the obligation to warn consumers. In a complaint to be filed today in Contra Costa County Superior Court, they say KEE has not lived up to the terms of the settlement because it has failed to post warnings on its Web site and elsewhere. Citing the litigation, KEE executives would not respond to questions.  Paintball was started in the late 1970s by two friends in the woods near Henniker, N.H., who held a duel using dye-capsule pistols developed for foresters to mark trees for cutting.  Since then, masks and protective vests and gloves have sharply reduced eye injuries and bruises. In addition, closer supervision has been imposed at paintball parks, where rules governing distances between shooters and targets have also helped to curtail serious injuries.  Still, paintball players must continue to unscrew their guns’ compressed-gas cylinders for recharge during play and at the end of the day. The valve design that proved deadly in the Contois case can loosen on the side that keeps gas under pressure in the cylinder. A player can then unwittingly release the valve, turning a charged cylinder into a dangerous rocket.  The problem is compounded by young paintballers’ frequent modification of carbon-dioxide-powered guns, in which a part called an antisiphon device is added to prevent jamming and increase the weapons’ performance. One such modification had been made to the gun whose cylinder killed Ms. Contois.  Rather than carbon dioxide, many guns now use compressed air. Because an antisiphon device has no role to play in these guns, they do not inspire modification, though their cylinders too can cause accidents.  While manufacturers have designed better valves since Ms. Contois’s death, by all accounts hundreds of thousands of the older ones are still used by paintballers. “There’s no way to reach them, because we don’t know who they are,” said J. J. Brookshire, chairman of the paintball subcommittee of ASTM International, a group that sets voluntary standards for a wide variety of products and services.  Mr. Brookshire said that the industry had improved consumer information about this and other safety issues and that technicians at the centers where paintballers must go to refill cylinders are trained to spot loose valves or those of old design. Further, standard 20-ounce carbon-dioxide cylinders must be refurbished or replaced every five years, a timetable that will eventually eliminate the old valves.  Yet any canister under pressure can be dangerous. “This is certainly the most dangerous hazard” for paintballers, said Scott J. Wolfson, a spokesman for the Consumer Product Safety Commission. After accidents that were caused by a faulty valve mechanism different from the one in Ms. Contois’s death, Brass Eagle Inc. of Bentonville, Ark., recalled 243,000 of its paintball guns. Those guns, safety commission officials said, had been responsible for at least 73 accidental gas-cartridge ejections, in which seven people were injured.  More than 10 million people play paintball in the United States, according to the Sporting Goods Manufacturers Association. “Every weekend there’s millions of cylinders being screwed in and screwed out” without incident, Mr. Brookshire noted.  But sticking to rules does not always come easily to young paintballers. The alteration to the cylinder that killed Ms. Contois is cheap, with do-it-yourself instructions on many Web sites. But it requires removing and replacing the valve, and unless done correctly, this can allow a valve to work loose over time. The dangers are rarely discussed in safety information given to paintballers.  The industry has not adopted a wide-ranging standard for such information, though doing so has been under discussion since a 1990 accident at a paintball park in Corona, Calif., in which Eric Hewitt, then 19, suffered a broken jaw and the loss of six teeth that could not be replaced. Mr. Hewitt, who still bears a scar, says his face is often numb or painful, and people notice the missing teeth.  “They kind of look at me funny,” he said, “and then they ask.”  He never played paintball again.  Nor did Jeff Weaver, the owner of the park where Ms. Contois was killed. After her death, Mr. Weaver built enclosed stations where trained workers removed and replaced cylinders for players. And when one manufacturer began marketing a valve that would safely discharge gas before detaching from the cylinder, Mr. Weaver gave $10 rebates to paintballers who traded in their old equipment.  But the best cylinders, he thinks, would be tamperproof, preventing young paintballers from modifying their guns. “You’re dealing with people who are getting on the Internet,” he said, “and they’re saying, ‘Hey, man, I want to make modifications to my stuff.’”  Mr. Weaver closed his park six months after the accident and now works as a carpenter.  “I pretty much lost heart for the whole thing,” he said.  A version of this article appears in print on , on Page A16 of the New York edition with the headline: Paintball Accident Made Him a Widower, and Then a Crusader. Order Reprints| Today's Paper|Subscribe
A man who lost his wife after an accident involving a paintball gun’s pressurized cylinder has turned up the heat on a company that had agreed to issue safety warnings to consumers.