(FORTUNE Magazine) – Most investors who end the year doing twice as well as the market would break out the Veuve Clicquot. Not Warren Buffett: ''Nineteen ninety-two will be worse than average,'' says the Oracle of Omaha. ''It wasn't remotely close to our best year'' -- 1976, when the book value of Berkshire Hathaway, his conglomerate, was up 59%. Buffett likes to gauge his performance by changes in the company's book value, because that measure takes in both operating earnings and Berkshire's investment results. For 1992 Berkshire Hathaway's book value will climb an estimated 15%. That's more than twice the likely 7% total return for the shares in Standard & Poor's 500-stock index -- but about nine percentage points below Berkshire's average annual compound growth rate over the past 27 years. One huge reason Buffett only doubled the market this year is that his biggest holding by far, Coca- Cola, went flat. Buffett did have some master strokes in 1992, which helped drive Berkshire shares up 24% -- from $9,050 apiece to $11,205 in mid-December. One was snapping up 4.3 million shares of General Dynamics last summer at about $72 a share. After the company announced it would sell its fighter plane business to Lockheed (see Defense), the stock closed as high as $103. Result: a $130 million gain for Berkshire Hathaway. Buffett's company also made $100 million from a 30%-plus appreciation in Wells Fargo stock and almost $175 million from a 14% climb in Capital Cities/ ABC shares. The real lollapalooza, though: a profit in the neighborhood of $750 million from a 53% rise in the stock of insurer Geico. With Berkshire's investment portfolio now over $10 billion, Buffett says the company will be hard pressed to match its record of the previous decades. ''That much capital is like an anchor,'' he says. ''You can still move around, just not as fast as you used to.'' Even so, few doubt that Buffett will have some humdingers in 1993.