Three first-generation Americans from a smoky Allegheny valley find themselves in the smoking marshes of Vietnam. The question asked in "The Deer Hunter" is what they are doing there -- not in the political sense of that question, but in the bewildered, panicky nightmare sense of "What am I doing here? "

Life is crude but comfortable for the Russian immigrants who work Pennysylvania's fiery steel mills and hunt its breathtaking mountains with rough camaraderie. Rituals from the old country, in church and social hall, give cohesiveness to their lives, to which they have added a simple and shining American patriotism. Whatever anguish comes of peasants being at odds with their government is firmly in the pre-American history of these families.

When America sends them to Vietnam, they go with pride.

Half of Michael Cimino's beautiful film documents this life the way a Dutch canvas might show a range of typical peasant moods and activities with the central excuse of displaying a community in festivity. For an hour and a half, the movie focuses on a wedding, but teems with dozens of tiny episodes, such as a beribboned bridesmaid's escaping a beating by her father to spend a carefree evening dancing, or men's faces glowing with cozy friendship and liquor. From this jolly crowd scene, a few men ascend to the heady stillness of mountain hunting.

The film then moves to Vietnam, where other rituals and other sports are taking place. These are the pursuits not only of an alien people, but of a civilization broken apart by warfare. Having declared, in the context of deer hunting, that "One shot is what it's all about," the men are introduced by their captors to the ultimate one-shot game. They are forced to play Russian roulette with pistols against their own temples, for the amusement of the Viet Cong, who bet on the outcome.

The power of the film, which is considerable in spite of its apalling flaws, is that one sees, in a cultural rather than a moral context, that elements of their civilized American life are present in the crazy chaos of wartime. The bonds the men share, their sense of apartness from others, their relish for tests of strength, the limits of their strengths -- all these move from the ordinary setting of peacetime home to the horror of a foreign war. This is not to say that shooting deer leads to shooting people; it merely demonstrates, dispassionately, that the human instincts involved in one may be stretched and adapted to the other.

Three men are shown making this shift from Pennsylvania to Vietnam: Steven, who goes to pieces emotionally and physically; Nick, who accepts the standards of war so completely as to lose completely his sense of peacetime realities; and Michael, who learns the lesson of stretched limitations and therefore survives.

Because all three are played with an articulateness of spirit, rather than words, they are stunningly effective. Robert De Niro's Michael has a fineness that becomes ennobled with experience; Christopher Walken's pale beauty becomes shockingly vulnerable; and John Savage's Steven is touched with sweetness. The luminosity of Meryl Streep lends some of their dignity to the sketched-in role of a woman waiting at home.

So much artistry has gone into this film that its lack of artistic discipline is a crime.

It desperately needs cutting.Identical points are made and re-made in this three-hour film, of which the essentials comprise about two hours. As one of these points is Nick's going berserk, one can only suspect that the filmmakers were willing to sacrifice artistic economy for the sake of repeating their most violent scene over and over.

The soundtrack works violently against the mood of the picture. Its worst offense against taste is that the mountain scenes are filled not with glorious stillness, but with a vast and noisy choir. The entire film is loud and jarring.

Loose ends are strewn about, acting as false cues. Before the wedding, it is hinted that the bride is pregnant, but the bridegroom confesses to a friend that he has never made love to her. Presumably, then, she is pregnant by someone else. In this tiny, close-knit community, how is it that no one seems to know that she has another lover? And if so, what is that saying about the man who turns out not to be able to "take" the rigors of warfare? That he is a classic fool to begin with? It seems more likely that this is an aborted plot line.

Another such error is that Nick, hospitalized in Vietnam, takes out his wallet and looks at the picture of the girl back home. Later, when we have temporarily lost track of Nick, Michael, arriving home, takes out the identical wallet and examines the identical picture. In dramatic language, this must mean that Nick is dead. If it is intended to show that they both cherish the same girl, that we already know. But that they would keep identical photographs in identical pockets of identical wallets is ridiculous. As Nick is not dead after all, this is apparently the sloppy intention.

"The Deer Hunter" has been sweeping up film awards. There ought to be a special provision by which its makers are allowed to pull it back and perfect it before we declare it to be one of our best pictures.