Local laws enacted two years ago to crack down on fly-by-night dealers who were cashing in on the boom in gold and silver prices have paid off in hundreds of arrests and the recovery of hundreds of thousands of dollars worth of stolen goods, area police report.

Montgomery County's 14-month-old law has helped police there close 327 burglary cases, led to the arrest of 231 people, including six dealers, and helped police recover $385,000 worth of stolen gold and silver items, according Maj. O.W. Sweat, chief of detectives.

Other areas have not kept such detailed records, but authorities are universal in their praise of the laws. "The county's precious metals ordinance gave us the records we needed to find the stolen property and burglars," said Fairfax County police spokesman Warren Carmichael. He cited a March 7 burglary of a Centreville jewelry shop in which more than $10,000 worth of antique rings, necklaces and bracelets was stolen. Within five days, police had returned the property to its owner and an Annandale man has been arrested for the theft.

Carmichael said burglaries in the county dropped by 860 between 1980 and 1981 and the number of cases closed increased by 31 percent. "Without the precious metals law, we might still be looking for clues."

The laws were an attempt to eliminate the fencing operations and shady dealers who bought stolen goods--frequently operating out of motel rooms, trucks and mobile homes.

The laws generally require people selling precious metals or second-hand merchandise to present one or two types of identification, including one with a photograph. The dealer must then supply local police with the seller's identity and a detailed description of the merchandise.

Before the item can be resold, merchants in Maryland and Virginia must wait 15 days. District merchants must wait 30 days. Precious metals dealers throughout the area must make daily reports of their purchases to the police.

Although the precious metals laws have made the fencing of stolen property more inconvenient, local police admit the network of records set up by the laws frequently does not detect cases in which stolen items are melted down and sold. And the laws do not affect instances in which stolen goods are marketed in areas that have no precious metals laws.

To track down the accused Annandale burglar, Carmichael said detectives combed through files of dealer transaction records for antique jewelry items similar to those stolen in Centreville. The stolen items were found to have been bought by a precious metals dealer in Groveton, 15 miles away.

Using the name and address supplied by the merchant, police were able to make an immediate arrest. "We have literally dozens of cases in which information gathered under the precious metals law has led to burglary arrests," Carmichael said.

Purchasers' records are vital. "Most of our arrests have been as a result of dealers cooperating and keeping accurate records," said Sweat, who said there are 50 precious metals dealers in Montgomery County. "We can use those records to follow up and arrest the burglars or the person who bought the property that was stolen."

In Prince George's County, where 56 precious metals businesses operate, three county police detectives are assigned full-time to find stolen property and track burglary suspects.

Last November, a burglar stole $120,000 worth of silverware from an 80-year-old District man and sold it the next day to a precious metals dealer in Marlow Heights. The dealer included the purchase with his routine report to police, who matched the silverware description with a stolen property report from District police that day.

The silverware was recovered and the alleged thief arrested in two days.

Prince George's police detective Cpl. John A. Lew, who handled that case, said that the similar laws in Washington, Maryland and Virginia have created a kind of area-wide dragnet that frequently snares burglars within a matter of days as they attempt to sell their stolen goods.

Lew, who is assigned to the Prince George's police Oxon Hill office, attributed the closing of an average of 15 stolen property cases a month to the new law.

Since detailed records are key, police strictly enforce requirements that dealers' files be in order. Errors in the records can lead to arrest, as one dealer discovered last year.

"I guess the law is good because it helps people to get their stolen goods back," said Nathaniel Stevens, who buys and sells precious metals under the name King Associates in Hillcrest Heights. "But I've already been arrested twice and have paid out more than $1,000 in fines because I filled the reports out wrong."

Stevens said his arrests came shortly after the law was passed and before the county issued written guidelines describing how the records were to be kept.

Lew said he has arrested a total of eight dealers, Stevens among them, for failing to make proper reports to police or for buying merchandise from a minor.

In the District, police say the law helped in apprehending a known group of burglars. The thieves had managed to sell stolen merchandise and avoid arrest by using a series of phony names and addresses, according to Detective Robert W. Wells, assigned to the 3rd Police District. By searching dealer transaction records, police recently were able to recover 18 items taken in 12 different burglaries.

Those items led to the arrest of three men who later told police of 40 other burglaries they had committed in the District and of many others in Maryland and Virginia.

"We were able to get handwriting samples from the pawn tickets and fingerprints off of the some of the recovered items," said Wells, who said his office sometimes recovers as many as 60 stolen items a week as a result of the precious metals law. "Without the information from the dealers' records, those men might still be out there doing burglaries."