D.C. Police Chief Maurice T. Turner, after differing last week with Mayor Marion Barry on a sensitive gun control issue, promised yesterday not to publicly disagree with Barry in the future.

In a memorandum to Barry that the mayor released to reporters at his monthly news conference, Turner reiterated his view that District of Columbia residents should be able to buy guns as long as they are properly registered, a view not shared by Barry.

"My personal belief is that law-abiding citizens should be able to purchase firearms to protect their homes, and that all firearms purchased should be duly registered with the proper authorities," Turner wrote.

"This is my own personal belief and is in no way a policy statement for this department nor does it reflect the attitude of the department in enforcing the present Firearms Control Regulation Act," the memo reads.

"In the future," it concludes, "I will refrain from interjecting my personal views when they may differ from the city's official policy."

The mayor insisted yesterday that he had neither reprimanded the chief nor asked for the memo from Turner, who in the early stages of this year's campaign for the Democratic nomination for mayor, has emerged as an important political asset to Barry.

Barry distributed copies of Turner's memorandum after a reporter asked him about his differences with his police chief.

"I didn't request it," Barry said. "I assume it was his own idea . . . I didn't tell him how to write it."

The city's gun control law, which took effect in 1977, required the registration then of all currently owned handguns, rifles and shotguns. It also banned the sale or possession of additional handguns by private citizens and required residents to keep pistols unloaded and inoperable.

Last Friday, Turner told reporters he supported a proposal by D.C. city council member H.R. Crawford (D-Ward 7) to temporarily lift the city's five-year-old freeze on handguns to permit residents who illegally own guns to register them for use as protection in their homes.

Turner said then that the law has done "absolutely nothing" to keep criminals from obtaining guns to commit crimes. He said city residents "ought to have the opportunity to have a handgun and to legally use it in their homes."

Barry also has said that the law has not stopped the proliferation of handguns in the city. He contends, however, that the ultimate solution is enactment of a tough, federal gun-control law, and not the weakening of the city's ordinance, considered one of the most stringent in the nation.

The chief's polite public differences with the mayor last week on the gun-control issue placed Barry in a somewhat awkward position.

Major crime in the city went up 20 percent during Barry's first three years in office and has become a major issue in the campaign. Turner has become a highly visible figure as the mayor's chief crime fighter, and, according to one Barry political adviser, the mayor does not want to be perceived by voters as impeding Turner's efforts.

At a Citizens Association of Georgetown meeting Monday night, for instance, Barry praised Turner after the chief had been asked how much it would cost to buy extra radios and bulletproof jackets for his officers.

"Let me say that we have one of the finest police chiefs in America," Barry said pointing to the chief who, dressed in full uniform, has accompanied the mayor to some neighborhood meetings and candidate forums.

"I'm the one who hired him, who hired the police chief who is bringing the crime rate down, who understands what it is to be a full-time police officer, who has over 26 years experience in doing that."

Even one of the mayor's major rivals in the race, showed deference to the chief at Monday night's forum. After Barry had spoken, Patricia Roberts Harris went to the lectern and, in addressing the crime issue, turned to Turner and said the city government needs to further support "our fine police chief."

Her comments drew applause from many of the estimated 175 persons in the audience.