Johnny Gant won quickly last night at the D.C. Armory, almost before he had a chance to show why he sould get another shot at Sugar Ray Leonard's welterweight title.

Gant was awarded a third-round knockout over Larry Moore of Fort Bragg, N.C., when the D.C. Boxing Commission physician, Dr. Isadore Shulman, entered the ring before the bell for that round, looked into Moore's eyes and told Referee Joe Bunsa not to let Moore continue.

Moore went down twice in the second round, once while clinching with Gant and again near the end of the round from a right cross behind the ear.

Moore staggered as he walked toward Gant to offer congratulations.Shulman said Moore suffered a mild concussion.

"I could see the dizziness in his eyes," said the physican. "The pupil reaction was slow. He could have gotten hurt. It doesn't take many punches when a boxer is in that condition."

It was Gant's 46th victory against 14 losses and two draws. He weighed 146 pounds, nine more than Moore.

Moore lost his 20th bout against 32 victories and two draws.

Gant has been seeking a rematch with Leonard since he was knocked out by the champion in the eighth round a year ago.

Leonard was introduced in the ring, but when he went to Gant's corner, Gant hardly acknowledged his presence.

The champion kept busy automgraphing $1 bills during most of the show.

Leonard reported no new developments in negotiations for a title defense against Roberto Duran. He said of Duran's knockout victory last weekend. "He's rounding into better shape. He's getting trimmer and stronger."

Trim and strong enough?

For an answer, Leonard whacked his right fist with enthusism into his left pain while grinning disdainfully.

The crowd was estimated at 3,200 in preliminaries:

Jeff (The Kid) Passero, unbeaten welterweight from Mitchellville, Md., decisioned Lew Daniels, Trenton, N. J., in an eight-rounder, for his eighth victory.

Light-heavyweight Robert McFarland, Trenton, knocked out Javon Pratt, Washington, in the second round.

Welterweight Wilbert Thomas, Philadelphia, was disqualified when he climbed out of the ring in the second round during his about with Dale Staley, Forrestville, Md.

Middleweight Mario Maldonado, Trenton, knocked down Richard Jackson, Washington, in the third round and referee Harry Cecchini stopped the bout, awarding a knockout to Maldonado.

Middleweight, Craig Stevens, Washington, stopped James Lee, Philadelphia, at 1:19 of the first round when Referee Thomas Green halted the bout after Lee was knocked down once.

Bud Decker, Wilmington, Del,, decisioned Eddie Gray, Washington, in a four-round middleweight bout.

Middleweight Herb Wilens, Gaithesrburg, and Keith Broom, Washington, put on a four-round exhibition in which no scoring was kept.