They came not just from the Washington area, but from as far away as Pennsylvania, West Virginia, Delaware and North Carolina. With them they brought cameras, cassette recorders, autograph books - and the hope that "the biggest indoor country music show ever" would live up to its advance billing.

They were not disappointed: Saturday's two "Grand Ole Opry" shows at the Capital Centre were the real thing. While a skeleton cast was back in Nashville doing the regular Saturday night broadcast over WSM, 22 of the Opry's biggest names were on stage in Largo, giving 27,000 of the country music faithful a healthy dose of down-home picking and humor.

Roy Acuff, in his first performance out of Nashville in more than a decade, twirled his yoyo and did fancy tricks with his fiddle bow. Minnie Pearl wore her $1.98 hat and told jokes on herself. Grandpa Jones played banjo at 100 miles an hour. Bill Anderson charmed the ladies with his cheatin' songs. And Wilma Lee Cooper, widowed less than a month ago, did her best carry on without Stoney.

All in all, the crowd seemed to get exactly what it wanted and at $10 and $8-a head, the 17,200 who attended the evening show and the more than 9,000 who turned up for the afternoon performance had the right to expect lot. With each of the 16 acts on the bill performing four or five songs during their 10 to 15 minutes on stage - a pattern that is unusual in a concert situation, but standard at Opry broadcasts - each show ran approximately four hours.

Promoter Rudy Callicutt seemed to be a happy man too. The two shows grossed nearly $250,000, more than doubling the previous record for an indoor country music concert, set by Johnny Cash and Hank Williams Jr. in Detroit's Cobo Hall in 1968.

"I'd have spent $25 to come out and see this show," said Ronald Feldpusch, a 30-year-old mechanic from Chillum Heights, Md., who attended the evening show with girl friend Shirley Brown, 24. "The only reason I didn't make the afternoon show too was that I had to work. I've seen the Opry nine times in Nashville, and I just can't get enough of it."

Although the bill stressed country music's older names, Felpusch and Brown, whose favorites are Conway Twitty and Loretta Lynn, said they didn't mind. "If Tammy Wynette or Donna Fargo had been here," said Feldpusch with a grin, "they'd a had to tie me to my chair. Besides, I'm what they call an old-fashioned redneck anyway. Roy Acuff and Minnie Pearl will never go out of date as far as I'm concerned."

For some in the crowd, getting a glimpse of Opry favorites whose voices they had been hearing for years fulfilled a life-long wish. "I've been listening to the Opry ever since it started (in 1925)," said 66-year-old Thomas Blandford of Brandywine, Md., who came to the show with his wife, his two sons and their wives, "but I've never seen it before. I always wanted to, but somehow I never did. I'm having a real fine time, but I wish it weren't so loud."

Blandford's comment illustrated just how far the Opry, with its acoustic, purist beginnings, has gone in its attempt to adjust to the electronic era. Although the sound system - and sound level - was minimal by rock standards, Bill Anderson dared to bring a synthesizer on stage, and even such traditional performers as bluegrass king Bill Monroe were forced to cope with the vagaries of microphones and amplifiers.

Nor was the show free of that other bane of the entertainment lover: commercials. Instead of the advertisements for Prince Albert tobacco and Martha White flour that are part of Opry lore, one disc jockey after another plugged his show, his station or his pet project. It was too much for some of the children in the crowd, who retired to the Capital Centre concourse and the Pong games.

The music itself, though, was delightful, and the performers, looking out at a sea of leisure suits, seemed to enjoy playing to a large crowd. Some of them, in fact, simply wouldn't get off the stage when their allotted time was up."You can't blame them," said disc jockey Red Shipley, one of the emcees for the show. "They see 18,000 smiling faces, and they want to play all night."