The wraps are off Stockman's version of the Reagan Administration's early, improvisational days. In toto, the former budget director's critique is every bit as waspish and subversive as the two excerpts published last month in Newsweek. For all its score-settling asides on adversaries in the executive branch and on Capitol Hill, however, the full text offers an engrossing (and cautionary) behind-the-scenes look at how Washington actually gets down to business. As a practical matter, the so-called Reagan Revolution, i.e., ""a frontal assault on the American welfare state,"" seems to have been chiefly in the eye of beholders, including Stockman, a free-enterprise ideologue. Nonetheless, traditional conservatives joined forces with a small band of supply side intellectuals to push through the 1981 tax cut that cost the federal government 30 percent of its revenue. Stockman was getting a rude lesson in Realpolitik. The Reagan Administration's point man, he was responsible for slashing social programs to accommodate the tax relief and military buildup the President was determined to have. In fairly short older, he realized his assignment was mission impossible. As documented in a celebrated Atlantic Monthly article, Stockman quickly lost faith in the canons of supply-side economics--and his party. Republicans, he writes, ""would not disown after November 1980 the me-too statism that had guided (them) for all those years in the political wilderness."" Reagan. who declared ""giant entitlement programs like Social Security"" off limits for Stockman's budget-cutting efforts, is chided for his apparent inability to grasp the political consequences of the thoroughgoing reforms he appeared to espouse during the campaign. Whether the resultant deficits will produce the ""fiscal gridlock"" predicted by Stockman remains an open question. Arguable as well is the intensity of Reagan's revolutionary fervor; at least as likely is the possibility he's a pragmatic and flexible politician, not a true believer. Nor does Stock. man make any real effort to probe the American public's obvious resistance to radical change; with heartfelt exasperation, though, he indicts its elected and appointed representatives on charges of recalcitrance. Bismarck is supposed to have said that citizens should never be allowed to see how either their laws or their sausages are made. Were it not the fate of this revealing, if doctrinaire, tract to test the market its libertarian author so loves, government budgeting might be added to the chancellor's list.