"I get bloody annoyed," says Colin Gray, "when I'm on a panel with somebody who stands up and says, 'Nuclear war is likely to be bad for your health. The American public has known for 30 years that nuclear war is bad for your health. If you scare the American public--the average housewife--what is the ultimate result? What is the objective?"

With his Beatle-top of black hair and his abundant fount of nervous energy, Colin Gray is one of the new Washingtonians who give conservatism its youthful get-up-and-go. He is also one of the small fraternity of men who think about nuclear war for a living. These are men who, by and large, have grown accustomed to being called "hawks," but if you ask them to name a bona fide hawk--a hard-liner among hard-liners--the name that pops up as often as any is Colin Gray's.

It does not always pop up in a friendly fashion, for Gray has spent much of his career questioning the assumptions of his more moderate colleagues, and his questions have become harder and harder to ignore--thanks to the last presidential election and to what Gray calls the "Chinese water torture" that he and other like-minded outsiders have practiced upon the policy-making establishment in recent years.

Gray has been nominated to the general advisory council of the Arms Control and Disarmament Agency, and he has been engaged as a part-time State Department consultant on arms control. Still, even within the walls of the State Department--specifically, within the cold, bare walls of a temporary office in the westernmost provinces of the seventh floor--he minces no words. Analyzing his client's gyrations on MX-missile basing, he says: "They really shot themselves in the foot. They deserve to lose the program." This is the man, after all, who coauthored an article in Foreign Affairs with the attention-getting headline "Victory Is Possible." While he regards that as a "ghastly title" in retrospect, he remains unabashedly committed to views no president could ever publicly endorse--including the view that nuclear weapons are, in all likelihood, here to stay.

Most specialists would be happy to see their specialties thrust into the public spotlight as Gray's has been lately. But this 38-year-old English e'migre', who can rattle off strategies and counterstrategies at a pace calculated to make a Gatling gun drool with envy, finds the current fashionability of his field more troubling than gratifying.

"There's an obligation on the part of people who are genuine nuclear disarmers," says Gray, "to tell me how we live more securely in a nuclear-disarmed world which they really cannot verify. And there's no way they can verify the other people, who are not nice, well-meaning American nuclear disarmers."

"The United States can never, because of its political culture and historical culture, sign an arms control treaty intending to cheat," he says. "Given the character of our country and the openness of our political system, it would be very hard to hide nuclear weapons in this country without somebody blowing the whistle." The Soviets, on the other hand, would be under almost irresistible pressure to cheat, because "if no one has nuclear weapons and I've got five, it makes a tremendous difference. Now how do you live in a world like that? You can do a New Yorker Magazine writer Jonathan Schell and say, 'Well, we must abolish nation-states.' That's great and I can invent schemes like that till the cows come home. It just isn't where we are. It's not helpful. Briefing President Reagan on, 'Wouldn't it be desirable to get rid of the nation-state system?'--that is not on today's in-basket."

Nuclear weapons, Gray has written, "are not the problem. The problem of war, as political theorists and historians have endeavored to explain (apparently with little success, to date), resides obscurely in the malign and complex functioning of the very structure of interstate politics, in human nature, and in the domestic dynamics of states. These are the ingredients that produce war--weapons of all kinds give expression to these ingredients, no more and no less."

How does a man come to devote his life to the study of nuclear war?

"I think you'd probably have to put me on a couch and have a psychiatrist answer that," he answers. When the question is rephrased in biographical rather than Freudian terms, however, he runs briskly through the important items on his resume: doctoral dissertation at Oxford on U.S. defense policy in the Eisenhower administration, lecturer at the University of Lancaster in strategy and foreign policy, head of the strategic studies research program at the Canadian Institute of International Affairs, Ford Foundation grant to study the history of nuclear strategy, assistant director of London's Institute for Strategic Studies, etc. Traveling Light

"I was fairly footloose and fancy free in those days," he says. "My wife and I packed two suitcases and there was no big deal, unlike now when you've got dogs, cats, fish, mice, children, everything. One can't move around that way now . . . I went back to England intending to stay in England, 'cause I'm British, but the jobs were not there. If you're interested in frontier-type subjects in the nuclear area, it's just the wrong country to be in."

So Gray made what he calls the "forced choice" to come to the United States, accepting an offer from Herman Kahn's Hudson Institute and remaining there for the next 5 1/2 years. Last year he received his citizenship papers and made another hard choice--to move to Washington and, along with several former Hudson colleagues, found a new think tank called the National Institute for Public Policy. "We hope the National Institute is going to be the first major think tank set up in 20 years," says Gray. "Because we are not Beltway bandits. We are nonprofit. We're not out to grab defense business and any contract that comes along. We are in the public education business. The key to our work is pragmatism and realism." The Skeptical Observer

Besides pragmatism and realism, Gray brings a large store of skepticism to his duties as an arms-control consultant. He has proposed (in the February issue of Arms Control Today) a new measure of nuclear weapon-power called "standard payload," designed to cover strategic and theater forces in one package and thus give both sides more room for maneuver within a possible agreement. But "we have one overwhelming problem in arms control," he says, "and that is, we don't have the necessary leverage to negotiate seriously. I mean, we can be serious about our proposals. The question is why the Soviets should agree to them . . . That idiot Sen. Hatfield says, 'Let's negotiate about Soviet air defenses.' Since we basically don't have air defenses and they do, what is there to negotiate? To say in the American context that it's entirely possible that there will be no agreement as a result of START is, in a sense, countercultural, but it's probably true. We're asking the Soviets to give up things they already have for things we don't have."

"This isn't a government position," he adds hastily. "This is my personal position. I think in both INF Intermediate Nuclear Force talks and START we're entering a process for intra-alliance political purposes that has no chance of success."

Gray is one of those who argue that the U.S. nuclear deterrent suffers from a credibility gap. The Soviets, he says, have taken elaborate steps to survive a nuclear exchange. Because of these steps, Soviet leaders may be less afraid of war than U.S. leaders, which may tempt them to think they can "face us down" in Europe or elsewhere. To close this gap--and to better provide against the possibility, however slight, of limited nuclear war--Gray believes the U.S. must develop far more substantial war-fighting plans and capabilities.

On the offensive end of the planning spectrum, he thinks we can partly compensate for a Soviet edge in "crude muscle" by redefining our ultimate threat in a nuclear war. "We have to target, as discreetly as we can, the Soviet state as opposed to the Russian people," he says. "Now we can only do that to a limited degree--the state is to a large degree co-located with the Russian people, unfortunately. But we think we're talking into the Russian value structure.

"When you talk about the Soviet government in a nuclear war context, you're talking about a distinctive target set . . . Let's suppose there were a hundred targets, and if we could hit all those hundred targets we'd get everyone in the Politburo, everyone in the Central Committee, we'd kill all the critically important bureaucrats, essentially we'd cut off the head of the Soviet chicken . . . "

On the defensive end of the spectrum, Gray would like to see us pay more attention to civil defense, air defense and anti-missile defense. These are things that have been largely ignored in the United States, says Gray, "because we have been required to argue--which we cannot--that there can be a perfect defense. We cannot keep Soviet missiles out of North America. We can keep some of them out. I want some kind of safety net even if it is a safety net with a lot of holes in it." Concepts of Survival

And he refuses to concede the moral high ground on this issue to the peace activists. "I agree with some of my Soviet friends," he says, "who will tell you privately and even publicly, sometimes, that it is the duty of a state to try and protect its citizens . . .

"What you are doing is making some modest or even immodest provision for the possibility that nuclear war could be limited, that the damage to which your society could be held liable can be controlled. In other words, it's a possibility. The other line of logic--the holocaust line--means the system, if it fails, must fail-deadly, and any nuclear war is going to be the end of the American experience, period.

"No one can possibly design a nuclear strategy that entails anything less than somewhere between five and 20 million front-deaths. If we could accomplish that in a major war that did not stop after a very light first round, we would be doing extremely well. And these are horrific numbers. Now if someone sees the possibility of nuclear war as the absolute evil, if they would rather the Soviets conquered Europe, maybe even conquered us, rather than that nuclear weapons be used--if nuclear weapons are that horrific, okay, we can abolish our nuclear weapons. If that is their position and they're consistent about it, then I am likely to be impressed.

"What I've got no time for is hypocrites, people who aren't prepared to think about it. When people start making moral gestures about freezes, which are not well thought-through, which are not obviously related to reducing the risk of war but if anything might increase it, and they don't have a story to tell on nuclear strategy or any real theory of how we get out of the nuclear-threat system in a reasonably confident way, well, I look for more rigor on the other side, shall we say."

A glance at his watch reminds Gray that he has a plane to catch--a plane bound for Westchester County, N.Y., his lame-duck place of residence. Abruptly, he begins cramming papers into his suitcase (which, accenting the sense of temporary occupancy, has been sitting by the office door). Cleaning off a side table, he comes across a scrolled-up poster that proclaims, "The Soviet Union Needs You--Support a Nuclear Freeze."

"That's really a little crass for my taste," he says, displaying the unfurled poster. "Do you think it's a little crass?" He furls it up again and stuffs it into the suitcase.

Downstairs, pressing his way out through a revolving door to hail a cab for National Airport, Gray looks back at the imposing edifice and seems newly startled by his presence there. "I have to use my time the best I can," he says matter-of-factly. "When Walter Mondale moves into the White House in two years, that's the last they're going to see of me at the State Department."