After union activists at the federal Office of Personnel Management unflatteringly dubbed Donald J. Devine their "Turkey of the Month" in September, the OPM director drew a laugh by signing his next letter to them, "Your fine feathered friend."

The union, Local 32 of American Federation of Government Employees, had had several clashes with the tall, graying Devine and so welcomed his good-natured response as "kind of humorous," according to an AFGE official. But she has since stopped laughing.

For these days, eight months after Devine began his duties as the government's chief personnel officer, his stewardship of 2.8 million federal workers has taken a rather stormy, and, some say, predictable, turn.

The 44-year-old former University of Maryland political science professor is regarded by union leaders and some members of Congress as the most visible, combative personnel director in recent memory. He has been accused of mixing his devoutly conservative and antiabortion views with OPM policy-making, and his bitter struggles with employe groups over cuts he ordered in health benefits have kept him in and out of court, helped throw the federal health insurance program into turmoil and led to some talk in Congress of curbing the agency's powers.

In his defense, Devine said in a recent interview that his actions have been cost-cutting measures aimed at fulfilling the goals of his budget-conscious boss, President Reagan, whose election he has called a "mandate for fundamental change in the way government works."

The OPM director is presiding over some tough times for federal workers. He has the tense, and thankless, task of overseeing not only the government's health insurance program, but also its reductions in force, job placement efforts, employe performance appraisals and much-criticized wage scales.

How he has conducted himself in this sensitive role has aroused anger among union officials. "No director of OPM or chairman of the old Civil Service Commission has ever misused his authority in such a capricious fashion," Vincent L. Connery, president of the National Treasury Employees Union, told a congressional subcommittee last week. "What we are faced with here is an appointed official whose mindset rests firmly in the 19th century."

And AFGE, the nation's largest federal employe union, has called for Devine's resignation, saying his handling of the federal health plan has jeopardized coverage for 9.2 million government workers, retirees and dependents, including more than a million Washington area residents.

Said Devine: "I think I've taken the most responsible course open to me, and I feel members of Congress, the major actors, at least, now understand what we're doing and are very sympathetic."

A former GOP candidate for Maryland comptroller, Devine brushes aside suggestions that his personal philosophies have colored his OPM decision-making, saying only that "in one sense, everything you do is ideological." He defends health coverage cuts, which have brought him the most criticism, saying it would cost the government $440 million if benefits were kept at the current level. And he argues that his zeroing in on abortion coverage came about because "I felt and still feel that when you're cutting all benefits, abortion is the least important thing."

His critics, however, while conceding the unprecedented difficulties Devine has faced in the federal government's retrenchment, say his attempt to curb abortions is an example of how he takes on battles as opposed to having them thrust on him.

Those who recall Devine's political greening in Maryland say they are not surprised that this perfectionist and true believer has become mired in political controversy while holding a supposedly nonpolitical, $60,662-a-year job.

"He has these deep-seated feelings on philosophy, and this is reflected in some of the things he is doing at OPM," said Maryland GOP chairman Allan Levey, a moderate who beat the conservative Devine in a close contest for that post three years ago.

Levey supported the conservative Devine's OPM appointment -- it was the highest administration job given anyone from Maryland -- as well-deserved for his loyal and hard-working support for Reagan. But many other GOPers in the state predicted trouble, remembering a number of celebrated internal party tiffs caused by what they described as Devine's authoritarian political style.

Devine's Maryland critics, mostly Republicans, using some of the same words that his union adversaries now employ, depict the OPM director as " an "awfully pushy" right-wing ideologue who is "bent on winning battles and losing wars." Supporters see him as a "committed conservative" with the "guts to tackle some political hot potatoes."

"I don't see very much difference between OPM cutting abortion coverage and Congress cutting out Medicaid abortions," said Joe Ayd, a Maryland attorney who is on the state GOP finance committee. "More power to the federal agency head who's got the courage to raise the issue -- it's his job."

Jackie Phillips, a field director in Maryland for George Bush who came over to the Reagan campaign, says she did not find Devine to be an inflexible conservative. "We had our differences, but I thoroughly enjoyed working with him -- and I was surprised."

She and others who know Devine expect him to run again for higher office. "Gubernatorial or Senate or Congress, not anything lower. He loves politics," said Forbes Blair, who chaired the GOP effort for Reagan in Montgomery County while Devine was Reagan's 1980 campaign director in Maryland, West Virginia, the District of Columbia, and, for a time, Delaware.

His credentials as a "pure" Reaganite have never been questioned. His national conservative affiliations have included membership in the American Conservative Union and service as special assistant to Reps. John Ashbrook (R-Ohio) and Philip Crane (R-Ill.). He also is a former director of Life-PAC, an antiabortion group, was once a consultant for the National Right to Work legal defense foundation and used to be an advisory board member of the Young Americans for Freedom.

At OPM, Devine has surrounded himself with a conservative inner circle, according to employes at the agency, who say this has cut him off from career personnel experts whose advice might have avoided some of OPM's confrontations with unions.

Devine says he wants to focus on "bedrock personnel questions" and "reduce paperwork and regulations that aren't necessary." He also is trying to build morale among beleaguered federal workers and to this end has supported pay increases for the government's senior executives whose salaries have been frozen since 1979.

In a recent letter mailed out under OPM's letterhead to several hundred of his political and academic contacts and each signed personally, Devine said that his agency has helped "get the bureaucracy under control." He cited as accomplishments OPM's presiding over "significant" government employe layoffs, the dropping of abortion coverage in most federal health plans and the agency's own budget and workforce reductions.

Some of Devine's detractors say that this letter illustrates not only how his philosophies become part of his OPM operations but also how he is using his job to build political contacts.

"He's gone out of his way to earn a gold star from the administration," said one staff member of a congressional oversight committee.

Although Devine headed Reagan's OPM transition team, his appointment as OPM director was by no means certain. Some Republicans say his cause was helped in part by ties to Reagan's "Kitchen Cabinet" and by an Evans and Novak column that championed his appointment and concluded, "Can Reaganism without Reaganites survive as a government policy?"

Some who have read Devine's books on politics or heard some of his speeches -- in April he said Reagan's election represented "a turning way from the New Deal flirtation with central government planning, alternative nonfamily life styles and value relativism" -- are skeptical about Devine's ability to separate his personal beliefs from his OPM actions.

They point out, for example, that Devine worked hard to get most of the employe groups to agree to drop abortion coverage even though insurance carriers say it accounts for less than 10 percent of health care costs. Some congressional sources expect Devine to issue a new set of eligibility requirements soon that would drop Planned Parenthood, a leading advocate of birth control, from the annual government-wide charity drive, a suspicion OPM will neither confirm nor deny.

When Devine ordered the 126 health plans in the Federal Employees Health Benefits Program to reduce benefits by 12.5 percent (while raising premium costs more than 9 percent), he said he was forced to do so because of rising health costs, the long neglect of fiduciary responsibility by previous administrations and OPM's own earlier misestimates of premium costs, 60 percent of which are paid by the government.

"The day is come where the bill is due," Devine says, adding that his negotiating posture with employe groups has been to "express your preference in a strong way . . . . We've offered to bargain -- the unions have insisted on keeping what they have."

Employe groups counter, however, that Devine "bullied" them into accepting abortion, mental health and other benefit cuts by threatening to kick them out of the program.

"You call it negotiations when all you get are ultimatums?" protests Dr. Edward Hinman, executive director of the Group Health Administration of America. "A lot of us signed under duress, then started fighting."

OPM has lost almost all of its court battles with the unions, which have rushed to court in eager competition to protect health insurance benefits that could attract new members. The agency is appealing a federal ruling ordering the agency to hold a two-week open season insurance enrollment period, postponed by Devine, so federal workers can shop around for better or cheaper coverage.

Unions and some Democratic members of Congress say the OPM director could have handled the health plan difficulties without resorting to drastic benefit cuts that, in the words of Rep. Steny Hoyer (D-Maryland), "are using federal workers as a fiscal scapegoat."

Even neutral and pro-Devine participants in the health care controversy say the OPM director's tactics were heavy-handed and exacerbated his problems with stubborn union leaders. His attack on a federal judge after an unfavorable ruling -- he said the judge had "usurped" his constitutional authority -- stunned Justice Department attorneys set to face the same judge the next day and is cited as an example of Devine's shoot-from-the-hip style.

A Brooklyn native educated in New York, Devine holds a doctoral degree in political science from Syracuse University. He moved to Maryland in 1967, settled in Wheaton and joined the faculty of the University of Maryland, where he is now on leave as associate professor of government and politics. He and his wife Ann have four children.

Devine first surfaced as a political strategist in James Gleason's successful 1970 campaign to be Montgomery County's first county executive. He was Reagan's state campaign chairman in 1976, when most everyone else was pushing for Gerald Ford. In 1978 he announced his candidacy for governor, then lowered his sights to undertake a losing race for comptroller against the popular Louis Goldstein.

By 1980, Devine was hard at work again for Reagan and was rewarded with the OPM job, which he assumed last March. Never part of the White House inner circle, Devine had a good deal to say about Maryland patronage at the start of Reagan's term, particularly if he wanted to stop some administration appointments, according to several Maryland Republicans. These days, however, there are fewer jobs to pass out and hopefuls must go through both Maryland GOP chairman Levey and Devine, a situation that has nevertheless made Devine critics cautious.

OPM watchers say it's too early to tell if Devine will get his gold star from the Reagan administration, but they know he is getting some unprecedented attention for an OPM director. They say it is almost as if Devine took to heart his own campaign strategy.

"To me," he told a reporter during his race against incumbent Maryland comptroller Goldstein, "the major thing is you've got to let people know he's got an important office."