Carol Burnett's hair does not look the way it looked for 11 auburn years of "The Carol Burnett Show" on CBS. "It's my own," Burnett declares, leaning forward and parting it with her fingers. "See the gray? Look, there it is! I'm proud of it."

It was a dark night for television when Carol Burnett left the air last year, but not quite so dark for her.She expanded her range in movie roles ("A Wedding"), discovered activism on behalf of the Equal Rights Amendment, and let her hair return to its original brown. And gray. "Twenty years ago they dyed it orange for the musical 'Once Upon a Mattress,'" she says, "and it's been various shades of red ever since."

On Sunday night, Burnett makes her most daring leap yet; she plays the part of Peg Mullen, whose son was killed in Vietnam, in "Friendly Fire," a three-hour ABC movie from the book and New Yorker articles by C.D.B. Bryan. This film, written by Fay Kanin-who has joined Burnett on a stopover in Washington-is perhaps the most straightforward and heartbreaking dramatic work don eon the Vietnam war and made available to a mass audience.

It is better than "The Deer Hunter" and "Coming Home" put together, and it could have a far greater effect on the country, since 50 or 60 million Americans may tune in to watch it on the same night. "Friendly Fire" has the impact of a death in the family. And Burnett completely transcends her old image as the knock-kneed zany who fell into potted plants after Harvey Korman opened a door in her face. Burnett, 44 now, looks anything but gangly or whacky. She looks smart and serene-even though her husband producer Joe Hamilton, is upstairs in his hotel room with a bad back and the two of them plan to take their 15-year-old daughter, Carrie, to Europe on Friday to shop for schools. And, Carol Burnett looks pretty-pretty in a satisfied and uncomplicated and comfortable sort of way. Pretty? She's beautiful.

Yet she may not be the first person who would pop into everyone's mind as the perfect Peg Mullen after they'd read "Friendly Fire." How surprised they will be by her performance, probly the best of her career. Burnett herself is not worried that people will be confused by this change of image.

"I think they're just going to be carried away by the story, I really do," she says. "As far as I know, this is the first film about the war from the point of view of the people at home, which I think is going to touch people. And one of the last lines is something nobody can argue with, when Peg says, 'When it's your son, there's only one side,' whatever you may think about war games or politics or who's right and who's wrong.

"There's no question about my 'image' in my mind. I don't believe in limiting oneself, and it's sort of a pet peeve of mine the way American show business mucky-mucks in business suits categorize people. I love comedy, but who not do other things, too? I like the British attitude. Glenda Jackson does a play for three months, then she'll do television, then she'll do a nightclub act, and then if she joins the circus, no one thinks a thing about it."

Burnett has not met the woman she plays in the film, Peg Mullen, who refused to accept the Army's version of what happened to her son. the Mullens' campaign to learn the truth about their son's death turned into one of the first antiwar protests to arise from within the so-called "silent majority." In fact, the Mullens are known to have been displeased with the Bryan book and reluctant about having it turned into a television show.

Kanin says, though, that "they have made their peace" and that "they were ecstatic about Carol" playing the part. The role of Mr. Mullen is played by Ned Beatty, who is brilliant as all get-out.

"Peg just wrote me a note," Kanin says. "It's a beautiful letter saying they made their peace with the fact that it's going to be on television and as a matter of fact, they even offered us the use of their farm in Iowa to shoot in. Pat, the oldest daughter, read the script and made some comments which were very helpful. Peg said they didn't want to go through all that pain again, but they see what's going on in the country, and think they see a kind of rise of militarism again, and that maybe the movie can say something."

"I think there's a whole campaign in some magazine saying the Mullens refuse to watch 'Friendly Fire,'" says Burnett skeptically. "I think it just makes very good fodder and I think it's totally exaggerated." Mr. Mullen did tell Kanin that he would not watch the program on the air but would videotape it and save it until the day he felt he could watch it.

The Mullens lost their son in 1970.

For Burnett, the change of pace is more than a switch from comedy to drama. She has not been associated before with material of such social consequence. She would sometimes end her TV show with a "save-a-tree" ecological remark, but she was an apolitical public personailty.

"I was never outspoken politically because I felt I wasn't intelligent enough in that area to come out and start doing that," she says. "In my own way I would vote for the people who felt the way I did. As a performer, I was always nervous that, well, suppose I made a wrong choice and I might sway a couple of votes the wrong way? Then I would be responsible. I didn't think we should use our show as a soapbox.

"Now, with certain things, I feel differently. Like ERA. I have come out because to me, that's not political. It's a moral issue. If I had three sons, I'd be out screaming about it. As it is, I have three daughters, and I owe it to women who aren't in show business and can't go to a bank and get a loan and not discriminated against, to speak up. I'm not the same person I was 15 years ago. I don't think any of us are."

She would like to meet Phyllis Schlafly, the obsessed ERA for. I might even pick up the check," she says. "I would ask her why she is doing this, because evidently she's supposed to be intilligent, and an intelligent person has to be for equality. So there must be an underlying motive she has-which makes her a very tough opponent. Like McCarthy.

"The dumb ones don't worry me because they just don't know what the amendment is, they haven't read it, and they just hear all this stuff about abortion, gay rights, and blah blah, and they'll say, 'Oh! I don't want to go to the same bathroom with so-and-so!' And who does? And who will? I think Mrs. Schlafly probably does not go to the bathroom when she flies because they all use the same lavatories up there. Those long flights must be murder for her. She's got to take the Concorde.And no liquids before she goes on board, either.

"I mean-for her to throw that out as an argument is so ludicrous. It's evil. I mean, it's so dumb!"

Meanwhile there are still more new roles for Burnett. She was one of the few bright spots in Robert Altman's hateful comedy "A Wedding," a big flop of last yeat which Burnett thought was not hateful and was fun to make, and she just completed work on another Altman film, "Health," a political allegory set at a health-food convention, in St. Petersburg, Fla.

"Glenda Jackson plays Stevenson and Lauren Bacall is Eisenhower," she explains. "I play a not-so-bright liberal who believes that anyone who's running for office and is good will win." She raises her eyebrows in a sarcastic arch. "She's a terribly dumb, naive person."

The trickiest scene in the film called for Burnett to dive into a swimming pool and discover what appears to be a dead body at the bottom. The problem is she has been terrified of diving ever since she was in high school gym class. "The teacher said 'dive' and I started to sneeze and I sneezed underwater. And I thought my ears were going to blow up."

Altman, stickler for realism if not for entertainment, insisted on the dive. "So all that morning, the rest of the cast are giving me dry-land diving lessons in the makeup room. They said, 'put up your arms' (she puts up her arms) and 'keep your dead down' (she lowers her head). And 'do this, do that.' And now comes the moment, and people staying at the hotel are standing behind ropes and watching, and I have not dived since Hollywood High.

"But, I did it, and I'm under water-not knowing that my rear end is right on top. I thought I was all the way under. And I swim over and see the body and come up screaming and, whew, it's over. And Bob comes over to me and says, 'Are you game for one more?' And I said, 'WHY???' And he said, 'It looked too good.'

During the underwater shooting, Burnett says she had to be weighted down because she kept bobbing to the top. Crew members joked that if they ever fell overboard, ethey would grab onto her.

Burnett's performance in "friendly Fire" is effective partly because she has come to represent on television an earthy, middle class and, though born in San Antonio, Tex., grew up in nothing more normal than Hollywood, Calif.-in a house one block from Hollywood Boulevard, at the corner of Wilcox and Yucca.

"I worked on the corner," she says, and then laughs a loud Carol Burnett laugh. "Hey, that's an exclusive! No, I mean, my first job was at the corner of Wilcox and Hollywood, at the Warner Bros. Theater, which is now called something else. I was an usherette. I saw 'Strangers on a Train' 57 times. In fact, I was fired because of it. This yound couple wanted to go in five minutes before it was over and I said, 'Look, it's coming on again in 10 minutes, it's a Hitchcock thriller, please don't go in.' The manager fired me on the spot. Sixty-five cents an hour, down the drain."

"I'll bet the male ushers got 85 cents," says Kanin.

"Seventy-five, eighty-five, something like that," says Burnett, not very bitterly.

Burnett wore a uniform with epaulets on the shoulders and when the manager fired her, he ripped one off. "Really. I'm not kidding," she laughs.

"So recently, about two years ago-three years ago-whenever it was, the Hollywood Chamber of Commerce calls and asks me if I would like to have a star on Hollywood Boulevard. And what's really funny is they ask you to pay for it; 'We want to honor you, give us a thousand dollars.' But it goes into the Hollywood Chamber of Commerce so I thought, okay, but only on one condition. I want it right in front of that theater where I got fired. And they did. It's right there."

There is a shameless gloat of victory. Burnett has bobbed to the surface again. In another moment she is posing for photographs and complaining about the ones ABC has used to advertise Sunday night's showing of "Friendly Fire."

"I saw that ad," sahe says. "Oh, does that stink! Ned and I knew it when they were taking those pictures. We said, 'Don't do this. It really looks like something right out of a movie from the '30s.' We said, "This is really like, Expression No. 42.'"

In the ad, Burnett is posed dramatically with a folded flag and Beatty stands behind her. It does look corny. The program is not. When Burnett saw the film for the first time, she cried, she says, especially when Beatty, as the father, came down a ladder outside his farm house and put on his hearing aid so he could hear the news that his son had been killed. Burnett's eyes tear as she describes it. This happens one other time, when she is recalling some of the many characters she played on "The Carol Burnett Show," and I take it upon myself to interrupt her.

"You're reminding me how much I miss that show," I tell her.

"Thank you," she says, her violet eyes glistening, and we all but melt into puddles right there. CAPTION: Picture 1, Carol Burnett, by Harry Naltchayan; Picture 2, In a scene from "Friendly Fire,"