SEATTLE – A lawsuit against the Maine-based manufacturer of the rifle used in the Washington, D.C.-area sniper killings and the Tacoma, Wash., gun shop that stocked the weapon could be broadened to include more victims and their families, attorneys said Tuesday.

Seven more victims or relatives of victims have asked to join the lawsuit, filed in Pierce County Superior Court in Tacoma last January by relatives of victims James “Sonny” Buchanan and Conrad Johnson.

Defendants are Bull’s Eye Shooter Supply of Tacoma, which either sold or lost the rifle in a theft; Bull’s Eye owners Brian Borgelt and Charles Carr; Bushmaster Firearms Inc. of Windham, Maine, manufacturer of the .223-caliber civilian version of the military M-16; and sniper defendants John Allen Muhammad and Lee Malvo.

Those hoping to join the case include Rupinder Oberoi, who was shot and wounded last September while closing his Silver Spring, Md., liquor store, and relatives of six other sniper victims.

Paul N. Luvera, an attorney for the families, said the court is set to hear a motion June 13 to amend the initial suit and include the additional plaintiffs.

The Brady Center to Prevent Gun Violence also is representing plaintiffs in the case. “By joining this lawsuit, these victims of gun violence are standing up for their legal rights,” Brady Center senior attorney Jonathan Lowry said in a statement. “They are also standing up to the gun lobby that is pressuring Congress to deny those rights.”

Legislation currently before Congress would protect gun manufacturers and sellers from such lawsuits. It is supported by the Bush administration and the National Rifle Association, but Senate Democrats have threatened a filibuster to prevent a final vote.

Malvo, 18, and Muhammad, 42, have been linked to 20 shootings, including 13 deaths, in Virginia, Maryland, Georgia, Alabama, Louisiana and Washington, D.C., last year. Prosecutors have said the three-week shooting spree was part of a scheme to extort $10 million from the government.

The lawsuit alleges that at least 238 guns, including the assault rifle, disappeared from the gun shop in the last three years. Despite audits by the Bureau of Alcohol, Tobacco and Firearms showing that Bull’s Eye had dozens of missing guns, Bushmaster continued to use the shop as a dealer and provide it with as many guns as the owners wanted, the suit alleged.

The amended complaint also asserts that law enforcement authorities have traced guns involved in 52 crimes to Bull’s Eye, including the Trang Dai Cafe killings in Tacoma that left five people dead. It also claims that Bull’s Eye failed to file required federal reports on firearms stolen or missing from its store for more than a year.

A call to Bull’s Eye Tuesday was not immediately returned.

Allen Faraday, vice president of administration for Bushmaster, has said the company did nothing wrong and sold the rifle legally to a firearms dealer.

Besides Oberoi, those hoping to join the lawsuit include:

. Ted Franklin of Arlington, Va., whose wife, Linda, was shot and killed while they were shopping at a Home Depot store.

. Lisa Brown, mother of a 13-year-old boy shot and wounded on a school playground.

. Margaret Walekar, whose husband, Premkumar, was shot and killed at a gas station.

. Carlos Cruz, whose wife, Sara Ramos, was shot and killed while sitting on a bench.

. Nelson Rivera, whose wife, Lori Lewis-Rivera, was shot and killed at a gas station.

. James Ballenger III, whose wife, Hong, was shot and killed outside a beauty store in Louisiana.