A Montgomery County judge yesterday overturned a county law that restricts sales of handgun ammunition to those participating in the state's voluntary gun registration program.

"It is a gun registration bill masquerading in an ammunition costume", Circuit Judge William C. Miller wrote in his opinion on the law, which went into effect last month.

The regulation of guns belongs to the state legislature, he continued, and the county council exceeded its power in attempting such regulation.

County Council President David Scull, the chief proponent of the law restricting sales of ammunition for pistols, said yesterday that he still believes in the idea.

There are about 200,000 unregistered handguns in Montgomery County, Scull estimated, or twice as many as are registered.

The law "would restrict the flow of ammunition--which is a dangerous material--to people who are responsible enough to participate in the registration program," he said.

The council "will certainly consider the possibility of appeal," Scull added. The council hired an attorney to represent it after County Attorney Paul A. McGuckian and Maryland Attorney General Stephen A. Sachs said they believed that the ammunition bill was illegal.

Under the county law, which did not apply to municipalities such as Rockville, where many of the county's gun shops are located, people had to show proof of gun registration in order to buy ammunition that could be used in a pistol.

Under state law, all handguns must be registered when they are bought at a gun store, but subsequent resale and private transactions require no registration.

Registration is not required for rifles and shotguns, but some rifle ammunition can also be used in handguns.

Attorneys for Atlantic Guns, Inc., a Silver Spring gun shop involved in the suit against the county council, told Judge Miller last week that about 80 percent of the store's ammunition sales would be affected by the county law.

William H. Randolph, vice president of the Montgomery Citizens for Just Firearms Legislation, which joined Atlantic Guns in fighting the suit, said that he was "really elated" by the judge's decision. He said that the organization had spent $8,000 battling the county council, all of it raised from mailings around the state.

Randolph, a gun collector who also enjoys shooting, called the law "mindless."

If the law had stayed on the books, he said, "it would have effectively opened up the doors for any kind of registration or gun control that you can imagine."

Ron Poling, manager of Crawford International, a Silver Spring gun shop that was not a part of the suit, said that yesterday's decision "makes us extremely happy. It's back to business as usual."

Poling estimated that his business has lost sales worth between $1,000 and $3,000 a week since the law went into effect Sept. 20.

"We're right in the middle of our hunting season, our big season of the year, and it hurt us bad," he said. "Fortunately, they got rid of it before the deer season."

Deer season starts one week after Thanksgiving.

Judge Miller stated that the county might have some jurisdiction over ammunition, but that "by requiring any person possessing an unregistered handgun to register it to be able to buy ammunition in Montgomery County is clearly regulating the possession of a handgun."