Washington lawyers are forever shuttling in and out of powerful political appointments, but rarely does a top attorney give up a lucrative partnership - and take a hefty pay cut - for a civil service job.

On March 1, Francis T. Vincent Jr., having resigned from Caplin & Drysdale, one of the city's top firms, joined the Securities and Exchange Commission.

He is one of a troika of associate directors in the commission's Division of Corporate Finance, which sees to it that U.S. companies make accurate and adequate disclosure of their affairs to stockholders. Corp. fin, as it is known, is one of five SEC divisions, and the three associate directors share the No. 2 spot in the division.

In a sense, by going from private practice to public service, Vincent is bucking the tide. The SEC has always been a launching pad, a kind of post-law school program between Harvard, Yale or Georgetown and the big money in top law firms.

At the SEC the young attorneys learn the many subtleties of the federal securities laws. Then they go to the other side where corporate clients pay generously for guidance through the loopholes.

Vincent, who is 39 years old, practiced securities law at Caplin & Drysdale and, before that, at Whitman & Ransom in New York City. "After 15 years of practicing law, I decided it was time to do something different," he says.

With his background in securities law, it's not surprising that, when he got the yen to join the government, he chose the SEC. For its part, the SEC and a healthy respect for Vincent.

In 1976, Vincent was appointed by the court as special counsel to Emersons Ltd., after SEC sued the Rockville restaurant chain, alleging civil fraud and kickbacks, among other things, by its top management.

As part of the settlement, Vincent was hired by the company to perform a thorough investigation and write a report of his findings. It took five months, and the results were widely praised within the commission.

Emersons has filed for reorganization, and Vinvent has never fully collected the fee agreed to in the court settlement. If any of the fees ever are paid, they will now go to the firm, not to Vincent. Last Tuesday, John Radnay, former chief executive of Emersons, was sentenced to four months in prison by a federal judge here for income tax evasion at filing false information with the SEC.

The Emersons report gave Vincent the reputation of a hard-nose among some fellow members of the local bar. The reason is that Vincent sharply critized the role of the company's outside counsel, although he was a member of a prominent Washington law firm and a former Justice Department attorney.

Coincidentally, Vincent approached the SEC for a job at the very time when Commission Chairman Harold M. Williams was kicking off a program to bring in talent from the outside.

Vincent, who did not commit himself to stay at the SEC for only set period, is the highest level outsider to be hired. The others are being brought in for two-year stints under fellowship programs being offered to accountants and lawyers.

"I don't want to appear as if I'm here to lobby for the private bar," Vincent says. "But I think my knowledge of how things are done by the private bar is useful to the SEC - including how business avoids doing some things."

"This is a particularly troublesome agency to some businessmen because we expect them, in effect, to disclose voluntarily their own sins. And that comes hard to businessmen," he says.

As for comparing his private and public practices, Vincent says: "The universe is much broader at the SEC because we deal with the whole range of American business.At a firm, by contrast, you deal only in a specialized area."

"At the law firm," he adds, "we focused on a particular problem for a client, whereas here we deal with a broad range of problems every day."

A RED-TAPE CUT: Small business executives have become increasingly concerned about the impact of government regulation.

More than 50,000 of these entrepreneurs have formed a National Small Business Association here and a new headquarters for the group was formally dedicated last night at 1604 K St. NW, in "operation cut red tape."

Said John Lewis, president of NSBA, "Instead of having a single ribbon-cutting ceremony, every guests was invited to cut some 'red tape' which is symbolic of one of our major missions, getting the government off the back of small business."

The group is lodged in a building that formerly housed South Korean businessman Tongsun Park's Pacific Development Inc. In addition to the association, the K Street office will house the Small Business Legislative Council, with a membership of more than 400 small business associations and some 4 million member firms.