"It really gets to you," said Marine Commandant Robert H. Barrow, standing straight as a bayonet as the drizzle continued outside his white brick residence. "My predecessor was here four years and it never rained."

Last night, at the commandant's reception for Secretary of Defense Harrold Brown, those undisciplined drops crashed his third reception in a row. Semper Fidelis.

As might be expected, members, exmembers and friends of the nation's amphibious force shook them off with no trouble at all while waiting outside for the evening parade.

Under a corner of one of the two blue-and-white striped tents, Secretary Brown and Canadian Ambassador Peter Towe discussed travel schedules to Ottawa and the constraints on diplomats.

Wonder, if a diplomat quoted another diplomat without naming him, whether anyone would give much credence to it," remarked Brown.

No one seemed to be lobbying him. "I'm easy enough to get in the daytime so they leave me alone at night," he said.

Howard K Smith showed up, surveying the reception outside from the back stairs of the commandant's antique-furnished home. He described the period since his abrupt departure from ABC News as "a relief."

It's good to be away from all those frictions," Smith said. Now he's looking for work again. Among his possibilities, he confided, is a position with the Washington Star.

Secretary of the Army Clifford Alexander braved the drizzle outdoors, as did Father Gilbert Hartke of Catholic University and Philip Merrill, publisher of the Washingtonian magazine. Inside, late arrivals included Senator John Warner (D-Va) and Elizabeth Taylor Warner.

Warner told a story of his brief fling with ditch-digging at the Marine Corps basic training school at Quantico: A superior officer ordered him out of the ditch as no place for any officer His wife thanked a young woman who told her, "I've loved you all my life."

Meanwhile, Secretary Brown, escourter by Gen. Barrow, enjoyed a tour of the commandant's spotless living quarters and viewed the numerous portraits of former commandants.

"What's the point of being commandant it you can't decide what to hang?" asked Brown

"I must say," remarked Brown to Borrow, "that the Chiefs deserve a great deal of credit for their SALT testimony. You said what you felt, you preserved your integrity and you didn't let anybody shake you."

As the skies began to darken, the guests moved toward the stands to watch the parade. The Warners joined the Browns and the Alexanders on the back steps.

"Whether the storm and stick by your position" Warner told Brown, chaking his hand.

"I haven't changed anything," answered Brown with slight mock offense. Everyone laughted.

Out over the barracks, as reception guests and visitors who had waited on line for hours began to seat themselves, the flag flew at half staff for Brig. Gen. Robert L. Denig Sr. He was one of the oldest living Marines until his death at age 94 in July. He was buried yesterday afternoon in Arlington National Cemetery. CAPTION: Picture, Secretary of Defense and Mrs. Harold Brown flanked by Marine Commandant and Mrs. Robart H. Barrow; by Ellsworth Davis