Several weeks ago, I reported to you on a letter circulated on stationery headed: "Robert C. Fox and Associates, attorneys at law, cousel to McGovern, Opperman & Paquin, attorneys at law, Minneapolis."

The subject of the letter was stated as, "Re: File 93-8EF-840-E3, Prize No. 49699K, Verification Code 173."

The letter began: "These law offices represent MCA Awards Clearing House in matters relating to the official notification of National Sweepstakes winners. You have been selected to participate. . ."

Many a heart began to beat more rapidly at that point in the letter, and many a recipient no doubt thought, "At last, after years of rotten luck, I have finally won something."

The remainder of the letter said nothing likely to change an optimist's notion that this might indeed be his lucky day. In fact, the only cloud in the sky was the sourpuss District Line, which said the letter was a clever device for getting the attention of people who were being solicited to visit the site of a real estate development in the hope they would buy lots.

Another cloud has now floated across this real estate project. The new cloud is cast by Tanick & Heins, a Minneapolis law firm. Tanick & Heins informs me that it represents the law firm of McGovern, Opperman & Paquin, and that MO&P "never authorized the use of its name in connection with this or any other such commercial venture. . . . Litigation on behalf of McGovern, Opperman & Paquin was commenced to rectify this abuse and prevent its recurrence. Injunctive relief was secured halting the unauthorized use of the firm name. . . . Commercial appropriation of a law firm name is an outrage and a danger to the legal profession."

Yeah. It is also confusing to recipients of mail solicitations who figure, "Gee, this must be legitimate. It carries the name of a law firm and was sent through the United States mails." THE NEW MARION BARRY

Even since Marion Barry stopped trying to destroy the establishment and begin trying to make it work better, this column has found his efforts worthy of favorable comment.

No political leader in the country could have cleaned up the mess in Washington in a dozen terms as mayor, let alone one. But Barry has worked hard, approached the city's problems with intelligence, been reasonably diligent in his pursuit of solutions and reasonably impatient with bureaucratic sloth. That's a pretty good combination.

However, in Barry's press conference this week, he said some curious things about guns, gun laws and crime.

For example, Barry admitted that the city's very strict gun law had not been effective. He doesn't think this had any significant effect on the increase in crime here, and despite the increase in crime he doesn't think we need a bigger police department. And, strangest of all, he urged owners of unregistered guns to give up their weapons voluntarily, although he admitted that when he was younger he routinely carried a gun. He said that on at least eight occasions he had faced guns that street toughs had pulled on him.

What we recorded in that story about Barry's press conference were the words of a man who was older and wiser than the young rebel who was known as a cop fighter and was once charged with trying to kick a police van into scrap iron. Today's Marion Barry is fed up with guns and shootings, and is looking for a social system in which people can survive in peace.

That's very laudible.

But alas! His formula for achieving it is not very practical.

I would like to put one question to the mayor: Back in the days when you were toting a pistol, if a mayor had asked you to turn in your gun at the nearest police station, what would your answer have been?

That's exactly the kind of answer you're going to get from today's street toughs, Mr. Mayor. To them, you are now the establishment they hate and fear. THESE MODERN TIMES

Bumper sticker spotted yesterday: "Remember, A Dollar Saved Is Worth 20 Cents." POLITICAL NEWS

Bob Orben says President-elect Reagan is proceeding very cautiously. "He just rejected Billy Carter's offer to be his brother."