You may never have heard of Lionel Callaway, but if you fudge about your golf handicap, he knows you, or your type.

Few realize that the Callaway handicap system was named after a person. Callaway, who served, for 40 years as taching pro at Pinehurst, N.C., invened the system in 1957.

"I'm still young," said the 83-year-old Callaway, while visiting his daughter, son-in-law and grandchildren in Fairfax.

The Calaway system, recognized and used by millions of golfers who don't have an established handicap, is handy at golf outings and field days.

It has another useful purpose: to prevent the age-old problem of the sandbaggng handicapper.

"You're handicapped after you play," sad Callaway. "I've been to tournaments where the prize offered is an automobile or a piano. When one of the big companies has their annual blowout, they all come. When they register, the guy says, 'What's your handicap? He looks over his shoulder and sees this big car and says, 'Oh, I'm a 30.' Its main purpose is to see that everbody gets a fair shake," said Callaway, who was an assistant pro on the Isle of Wight (England) before coming to the U.S. as a young man.

"It's so simple that people who run the tournament do it differently sometimes, and if you change it, it's no longer a system," he explained.

Without delving into the nuances of the system, if you shoot from par to 75, deduct half the score of your worst hole; from 76-80, deduct the entire score of your worst hole. it progresses up to 126-130, where you subtract your six worst disasters.

The key is that the system works, par is seldom belittled and you are spared the golfer with the sheepish grin accepting the winning prize of new golf clubs with a net score of 49.

Callaway, a collector of golf artifacts and gadgets, has made other contributions to the humbling game.

I've done a lot for golf," he said forthrightly. Among his inventions are a slide rule for Callaway computations (with profits earmarked for junior golf), a carpet putting cup with collapsible sides, a patented Form Finger Grip with raised surfaces encouraging the correct grip, rubberbased golf ball paint, and a canvas device that improves the swing plane.

"I don't want to make anything (money) out of my ideas," said Callaway. "I just want to give them back to the game. Golf has been good to me. A lot of these pros are making so much money today, but they ought to put something back in the game."

The Middle Atlantic Open begins tomorrow at Hobbit's Glen and Allview in Columbia, Md.

A field of 150 pros and 87 amateurs will play either course Monday, switch Tuesday, and all will play Hobbit's Glen in Wednesday's final round. Barry Fuhrman of Woodholme won last year. The total purse is $9,000, approximately $2,000 going to the winner. Part of the proceeds will go to the Howard County Lung Association.

Area golfers returned from the Porter Cup near Niagara Falls singing the praises of winner Bobby Clampett, the little Brigham Young player who was low amateur in the U.S. Open.

"Clampett is soooo good," said District amateur champ Wayne DeFrancesco, who trailed the winner by 18 strokes at 290.

Ralph Bogart, who finished third in the senior division at 301, was impressed with Clampett's ability to keep his cool during a disappointing round of 75. Clampett came back the next day with 62. He shot a finalround 65 to edge Jay Sigel by two strokes. Clampett sank long putts on the final four holes.

Peter McEvoy, winner of the British Amateur, will be the first amateur to compete in the World Series of Golf at Firestone, Sept. 28-Oct. 1.

McEvoy joins, among others, 1977 PGA and defending series champ Lanny Wadkins, Jack Nicklaus, Gary Player, Tom Watson and leading PGA money winner Andy Bean.

The winner of the U.S. Amateur at Plainfield (N.J.) Country Club, Aug. 29-Sept. 3, is also expected to be invited.