The Montgomery County attorney advised the County Council yesterday that a proposal to restrict the sale of ammunition in an attempt to control handguns is outside council authority and preempted by state law.

The opinion by County Attorney Paul A. McGuckian precedes a public hearing scheduled tonight on the bill, which was proposed by council member David Scull. The meeting, arranged after a packed hearing last month, has drawn 39 speakers opposing the bill and only one supporter--Takoma Park Mayor Sammie Abbott.

The proposal would restrict the sale of bullets and other "fixed ammunition," excluding flares and signal devices, to persons with registered handguns. McGuckian said that's the same thing as requiring registration and that state law preempts localities from regulating the transfer or possession of firearms.

"The General Assembly did not intend to leave with Montgomery County the authority to indirectly legislate a registration requirement for handguns," McGuckian wrote.

Since the opinion is only advisory, the council could still pass the bill, but that now seems unlikely since, if approved, it would almost certainly be immediately challenged in court.

"I just wish he had given us that opinion a month ago and saved the council a lot of hassle," said Scull's legislative aide, Karen A. Orlansky.

National Rifle Association members were pleased with the opinion. "I think the poor chap Scull didn't do his homework," said David Marshall, an NRA lobbyist. "If each community had the power to regulate handguns like they regulate the speed limit, we would have a patchwork of legislation. How would the police enforce it?"

Gun control supporters, who saw the Scull bill as an innovative attempt to circumvent the state law, said they were not surprised by the ruling. "The council is pro-handgun control anyway, so we think after the elections it will stand a better chance," said Rex West, field coordinator for the National Coalition to Ban Handguns.

Council members said they expect a large turnout at tonight's hearing in the 1,200-seat auditorium at the Richard Montgomery High School in Rockville, especially since the NRA has mobilized its members through a mass mailing. The council plans to broadcast the hearing into the parking lot outside.

The last attempt by a Montgomery County council to legislate gun control ended 13 years ago in the rejection of a strict registration ordinance, after three days of raucous public hearings packed with gun owners and enthusiasts.