Okay, sports fans. You've always wanted a piece of the pro football action. Now here's your chance to get in on the ground floor of the Washington area's second pro team. Want to invest? Try out for the team? Coach? Lead cheers? . . . But first, as the stockbrokers say, familiarize yourself with the prospectus.

The Virginia Chargers aren't in the telephone book yet and they don't have a stadium. So far, they've played only one game as professionals -- last Saturday night against the 1981 league champs, the West Virginia Rockets, in Charleston during a thunderstorm -- and they'd rather forget that one.

But head coach and owner Robert J. Shaw says things should be looking up. You can take a closer look at the Chargers this Saturday when they go against the Buffalo (New York) Geminis at 7:30 on Manassas Park High School field.

It's not as though the team sprang from nowhere. Its roots go back to 1970, when Shaw, who had played pro football for San Diego and Toronto and coached at Colorado State, decided to return to his native Northern Virginia. "I missed coaching, so I began coaching an 18-and-under 160-pound team for the Fairfax Police Youth Club." Eventually the league folded, but the Fairfax Chargers didn't.

Attracting post-high-school players, the team expanded its schedule to include college club teams in North Carolina as well as Virginia. The following year, the Chargers joined and became champions of the Mason-Dixon AA semi-pro league, and last year moved up to the AAA semi-pro Interstate Football League. This year Shaw's team joined the seven-year-old American Football Association, the only pro football organization outside the National Football League (unless and until the United States Football League kicks off next year).

The Virginia Chargers are one of six teams in the North division of the AFA. The others are the West Virginia Rockets, the Roanoke Valley Express, the Buffalo Geminis, the Racine (Wisconsin) Gladiators and the Canton (Ohio) Bulldogs. The South division includes three teams from Florida and one each from Georgia, Alabama and North Carolina; the Southwest division fields four from Texas, one from Okalahoma and one from Louisiana.

The teams play an end-of-May to end-of- August schedule; the playoffs pit two teams from each division plus two wild cards. The American Bowl is slated for August 21. Shaw's glad the Chargers were placed in the North division: "I didn't want to be playing those southern teams in 90-degree heat."

But of course Saturday or any night of a typical Virginia summer the Chargers could indeed be playing in an oven. A hot night might give them an edge against the more northerly Buffalo Geminis, yet even the hometown players acknowledge that playing in summer may have its drawbacks. Backup quarterback Jay Wilson, who played football for Woodbridge High School, soccer for Radford University and football during a two-year hitch in the Marine Corps in Memphis, admits that "it takes a lot of mental energy to play in 90-degree weather."

The Chargers, whose uniforms are "royal blue, Air Force blue, gold and white, with a lighting bolt down the side," are in serious need of a first-class stadium. Established AFA teams draw big crowds, Shaw says, when they play in locations such as the Akron Rubber Bowl, War Memorial Stadium, Legion Field, the Gator Bowl, Rice University Stadium. Last year's AFA championship playoff was at Chicago's Soldiers Field and drew 30,000. Shaw says AFA games-of-the-week are scheduled for cable television, but to encourage attendance, Chargers' home games will be blacked out here.

The size of the crowd is understandably important: each player gets one percent of the gate receipts. Shaw estimates that just fielding a pro team costs between $100,000 and $150,000, but "we're lucky because we had a lot of stuff on hand" from minor-league days. Still, he's eager to sell stock at $100 a share, per value one-tenth of one percent -- $1,000 makes you a one-percent owner. Investors are expected to help promote the team.

And, Shaw says, "We're still looking at players, still looking at coaches; we're pretty picky." He'd especially like more defensive linemen. Although one player, Annandale High School graduate Allen Little, started with the old Fairfax Chargers club team, Shaw's looking for players with college or minor-league football experience. He's also looking for more coaches to augment Carl Pregenzer, special-teams coach; Thomas Tate, defensive coordinator, and John Kraus, offensive line coach.

George Claffey, who played for West Virginia Wesleyan, is the placekicker. Shaw calls him "a super kicker, probably the best field-goal kicker in the league." Running back Harvey Banks was a high-school All-American from Arlington's Yorktown who went to Texas Christian, then transferred to Howard. Flanker Jeff White played for Wakefield in Arlington and signed a baseball contract with the Kansas City Royals, but decided to come back home. Wide receiver Freddy Bowen played for Arkansas State and fullback D.J. Jones for James Madison University. Two Marines stationed at the Marine Barracks play for the team, and there are police officers, firemen and teachers on the roster.

Because almost all have full-time jobs, the team practices Tuesday and Thursday evenings at Arcola Community Center in Manassas, where Shaw is supervisor. They'd like more practice time, but some have trouble getting to Manassas. One, a teacher who had been commuting from Princeton, New Jersey, has moved a little closer: he's signed up to teach in Annapolis.

A few have moved into the area to play with the Chargers to gain more experience before going on to the National Football League: wide receiver Larry O'Rourke is playing with the Chargers at the direction of the New Orleans Saints. Shaw says that the Chargers have "a good working relationship" with the Washington Redskins and other NFL teams. Tony Howard, the Chargers' wide receiver and an all-star in the Interstate league, recently signed a contract with the Redskins.

Playing 10 games from May 29 to July 31, the teams ride in rented buses and sometimes don't even stay overnight. Last Saturday the Chargers rode 71/2 hours to Charleston, played in the pouring rain, and rode the bus home again. Most of the players slept on the bus, Shaw said, but "I stay awake to make sure the driver doesn't fall asleep."

For fans in Panama City, Florida, or Charlotte, North Carolina, or Roanoke, Virginia, or Canton, Ohio, the AFA may be big stuff, but the Chargers are in Redskin territory. While the Chargers may have to play in five different stadiums this summer (all arrangements are pending), Shaw, ever the optimist, says that would help introduce the team to a wider community.

He's busy planning halftime shows for the home games -- "July 3 we'll have fireworks," he promises -- and hopes to negotiate discount promotional tickets.

This week, mainly, he's looking for office space. Until then he's working from home (703/754-9520, evenings) and by mail (Box 1188, Manassas, Virginia 22110).

WHEN AND WHERE IT HAPPENS -- The Virginia Chargers play the Buffalo Gemini at 7:30 Saturday at Manassas Park High School field (3,000 seats). Tickets: $4 students and senior citizens, $5 adults. To invest or to try out as a player, coach or cheerleader, call Shaw or Carl Pregenzer (703/221- 7276). Public relations: Pam Inglett (703/931-1120). Home games: the Wisconsin Gladiators June 12; Roanoke Valley Express June 26; West Virginia Rockets July 3; Canton Bulldogs July 31.