ANNAPOLIS, DEC. 6 -- A year after it took effect, Maryland's controversial handgun control law is under fire by gun control advocates and gun manufacturers alike, with both sides charging it has produced inconsistent results.

In a legal action scheduled for hearing Friday in a Baltimore court, officials from Marylanders Against Handgun Abuse contend that the law they fought for in a 1988 voter referendum is not being logically applied by the Maryland Handgun Roster Board.

The board was established under the state's handgun control law to sort through hundreds of makes of handguns and decide which should be outlawed for sale or manufacture in Maryland.

Although given nine general criteria by which to evaluate guns, the board has never developed precise standards for deciding what firearms to ban, the handgun control group argues. The result has been approval of 1,120 guns, including 11 from a Florida manufacturer that the group argues are clear examples of the Saturday night specials targeted by the law. The board has rejected 17 weapons.

"Quite simply, the rulings of the board to date have been ad hoc, inconsistent and conflicting, and its logic therefore incomprehensible," attorney Michael A. Pretl argued. Marylanders Against Handgun Abuse is asking a Circuit Court judge to reject the board's approval of 11 guns sold by the F.I.E. Corp., and order it to begin developing specific standards. Until such standards are developed, "the rulings of the board will continue to confound analysis and to violate important rights and interests of the community at large." Similar arguments are raised by the gun manufacturer, Beretta U.S.A. Corp., in its appeal of the board's decision to reject Beretta's Model 20 handgun. The Model 20, Beretta lawyer David J. Miliman argued in the case scheduled for hearing in court next week, is virtually indistinguishable from other guns approved by the board. An appeal from another gunmaker is scheduled for late January.

While Assistant Attorney General C.J. Messerschmidt defended the roster board's decisions, she said the panel was discussing a proposal by the gun control group to set up an advisory committee that would study whether more precise standards are needed, and how they could be developed.

"The board has informally indicated that it has no objection to looking at a proposal for regulations," Messerschmidt said.

The arguments are being raised at a time when handgun sales in Maryland have dropped sharply. After peaking about 33,000 in 1989, state records indicate that fewer than 19,000 handguns have been sold so far in 1990, according to Capt. Merrill Messick, commander of the State Police's Licensing Division. Messick said the reason for the downturn in sales is unclear, although he speculated that after an intense period of buying that surrounded statewide debate over gun issues, sales may have reached a saturation point.

The handgun law was the subject of Maryland's most expensive political campaign ever -- a $6 million effort by the National Rifle Association to defeat through referendum a measure approved in the waning days of the 1988 General Assembly session. Encouraged by Gov. William Donald Schaefer and other top state leaders, voters approved the measure by a comfortable margin.

But the law has been the subject of controversy since the board began its deliberations in early 1989. Gun enthusiasts argue that the law can never stanch the flow of weapons to criminals, and they contend that the board has discriminated in favor of major gun makers, approving numerous weapons made by some companies, such as Smith & Wesson, while subjecting the products of smaller firms to more intense scrutiny. Gun control advocates, while frustrated that the panel isn't more aggressive about pulling some models from gun store shelves, say the law has discouraged some of the country's least reputable gun makers from seeking board approval for their products.