Several weeks ago, when officers of Smith Barney, Harris Upham & Co. Inc. tallied up sales records of the investment firm's brokers across the nation, they had reason to focus attention on their downtown Washington branch office.

For the quarter ending in August, three of the local brokers were among the top 10 sales professionals in Smith Barney's 80 offices. During a period of heavy stock market trading activity, Washington brokers Len Feldman, Ron Needelman and Frank Joyce were ranked first, third and seventh, respectively, of the company's 1,100 brokers nationwide.

Given metropolitan Washington's status of affluence and more stock investments per capita than any other urban center, it may not seem unusual that Washington brokers should be on the Smith Barney list. But Feldman, Needelman and Joyce also may be the top three retail professionals in the city, in terms of gross sales production.

An annual sales volume of $300,000 is considered very good in the securities business. And, although actual figures are a trade secret, it appears that each member of the Washington trio belongs to that top category. In short, three brokers apparently account for close to $1 million of annual sales for their company.

"These three guys eat and sleep the stock market," is how Carlton Collins, vice president and resident manager of Smith Barney, Harris Upham, describes the sales dynamos, part of a staff of 20 professionals in the D.C. office, where sales in 1978 to date are 150 percent of the previous year's volume.

The three go to lunch every day, getting away from the office for about 30 minutes to gulp down sandwiches and exchange ideas. They agree on a lot and disagree on a lot. Each has staked out a business sector for specialization because of individual interest (Needelman, insurance; Feldman, banking; Joyce, computers).

They read thousands of pages of research reports and periodicals each week, often at night and on weekends at home, "accumulating knowledge about companies for recall over a long period, not short-term information for trading," Joyce said. Their favorite magazines (unanimous vote): Business Week, Forbes and Fortune.

In interviews last week, the three brokers all described themselves as "contrarians," seeking values where other investment specialists show little interest.They have built up a close relationship over four years of professional sales work together in Washington.

According to their boss, Collins, a Washington native who has been in the securities business here since 1962, the success of the three has meant big market profits for their clients. Much of their business in the past two years has been in over-the-counter and American Exchange stocks, shunned by many at first, but the market sector where "stupendous gains" have been made in 1978. Through last week, for example, OTC volume was 2.25 billion shares, 4 million ahead of the previous annual record in 1972.

The Smith Barney, Harris Upham trio obviously are something unusual in the business of securities sales. But they are not really a team. Each man has his own clients and a separate style of doing business. The knowledge of each man is shared with the others but there are no joint investment decisions.

There are other differences: Needelman, 32, a mative of Silver Spring, jogs six miles every morning to help himself cope with "a very pressurized business." Feldman, 37, a native of Bethesda, emphasizes the individual knowledge of his clients who "are very attuned to what's happening," often requiring three or four telephone conversations a day. Joyce, 37, originally from New Mexico, is in the office until 6 o'clock or later every business day. "The only thing I do is investments . . . I'm here one day on weekends . . . that's the way I am," he adds, after Feldman notes the time Joyce stayed overnight once during the summer, as well as early arrivals.

On investment philosophy, the three speak in unison, despite their individualism. Their common goal is to make money for their clients only buying and selling stocks. They have no other investment specialties (although Joyce follos commodities closely, for himself) and they do not think of themselves as market analysts.

Along with the other 1,100 Smith Barney, Harris Upham brokers, Joyce, Feldman and Needelman pay close attention to what their company calls "the investment list."

According to most people in the business, Smith Barney long has had some of the best and most complete research on Wall Street. Formerly a business oriented to institutional investors, Smith Barney moved into retailing and a full line of investment services in a 1976 merger with Harris Upham. But the retail offices (such as Washington) mine Smith Barney's research, which concentrates on a selected number of firms at any one time and provides daily reports.

Stocks picked for the firm's bimonthly recommended list are expected to produce total returns exceeding market averages over the next 6 to 12 months. There is several each of growth, growth-with-income, income and aggressive growth stock recommendations.

When certain issues reach a point where analysts for the firm believe no significant price appreciation is likely, they are deleted. Unceremoniously, stocks are dropped from the list at a moment's notice and the flash goes instantaneously to all retail brokers and institutional clients at the same moment. And the three brokers have their own recommendations.

Said Joyce: "It is not difficult to make an above average return in the market. A lot of people go wrong trying to make a big return, too fast. They get too exposed, there is extra risk." In line with this policy, the threemen have purchased no shares of the so-called gambling issues made "hot" by Atlantic City's legalized gaming.

These are some of the views expressed last week by the Washingtonians in a break from their sales work on K Street:

Feldman: It's described as a stock market but it's really a market of stocks, since the collapse in '74. There (were) a lot of emerging growth companies, totally ignored. We got in there really early and made our customers good returns in poor markets. As there were ups and downs, we stood there and accumulated good positions.

Joyce: We're all very risk conscious, focusing on the downside risk of any investment . . . No one has a 1,000 percent batting average. It's important, when you are wrong, to be able to admit it (to the client). You really have to say, 'I was wrong, we have to get out of it (a specific stock).

Needelman: When studying companies, we look for a situation where the stock is below book value, we find a leader in its industry and compare it with others in the industry . . . our basis for picking a stock is that we see a good uptrend in earnings, a turnaround situation, dividend increases.

Feldman: We liked Geico (Government Employees Insurance Co.) at depressed prices of about $5 two years ago. We saw it as a turnabout investment and took a substantial position for our investors.