A smiling, sociable Secretary of State Alexander M. Haig Jr., as if to prove he'd lost none of his diplomatic clout in the last few days, dropped in on a Turkish Embassy reception for Foreign Minister Iter Turkmen last night.

Haig's cool, comfortable appearance prompted one guest attorney Sylvan Marshall, to remark that he had looked cool and comfortable at the Gridiron dinner Saturday night.

"I'm always cool and comfortable," said Haig, a wry smile playing about his lips. "I just fire bullets for effect."

Did he feel as effective as he had four days earlier, a reporter asked.

"I feel very effective," Haig replied.

"Still in charge?"

"I feel very effective," Haig repeated, reaching out with a forefinger to touch his questioner's nose, then moving off to pose for pictures with Turkmen, whom he had invited to Washington.

While some among the 200 or more guests from Capitol Hill, the State Department and other agencies craned necks to get a glimpse of him, Haig calmly turned off reporters' questions about what had happened Monday in the White House Situation Room in the aftermath of the assassination attempt on President Reagan.

"Oh, I'm not going to talk about that," said the secretary when asked about a reported difference of opinion between himself and Defense Secretary Caspar Weinberger over who was in charge.

Nor would he make what he called "value judgments" on media coverage of what happened.

"Reporters write what they know and were told and that's the way it should be. Everything has been said that could be said on the subject -- and maybe a little more."

The Rev. Frank Haig of Baltimore's Loyola University said he had been "a little" disturbed at his brother's takecharge appearance on television Monday but had decided that he was tired. "Anybody would be tired after what happened. How did [ABC-TV anchorman] Frank Reynolds look?"

As for brother Al's habit of making headlines, well, said the Jesuit priest, chairman of Loyola's department of enginering science, computer science and physics, "it's a bad day when he's only on the second page."

Earlier, Attorney General William French, Smith talked about another aftermath of Monday's shootings, the "epidemic proportions" he said violent crime has now reached and the role the federal government may take to control it, "though essentially it's a state and local matter."

Might the president change his mind about gun control, someone inquired.

"I doubt it, I doubt it," said Smith. "He is satisfied, as am I, that the problem is not so much gun control as in the sentencing area. And until we become severe in our disposition of people who use hand guns, we're probably not going to make much of a dent of the problem."

Over in the receiving line Foreign Minister Turkman, with Turkish Ambassador and Mrs. Sukru Elekdag, welcomed a cross-section of present and past Washington officialdom, including Chief of Protocol Leonore Annenberg, undersecretary of state for political affairs Walter Stoessel Jr., former undersecretary of defense Robert Komer and former assistant secretary of state george Vest. ("I'm what you call in between assignments," said Vest, "so you name it and I'll take it.")

After Haig arrived, the line started floating with him as he drifted through the crowd. Eventually, he and Turkmen wound up in the drawing room sipping Turkish wine and balancing plates of chicken and rice on their knees, the second time in the day they had eaten together. Over lunch they had discussed the situation in the Middle East and Turkey's role as what Haig called "the southern anchor of our NATO alliance," one the Reagan administration hopes to bolster with an estimated $700 million in military and economic aid budgeted for fiscal 1982.

Haig said he'll see President Reagan before leaving tomorrow on his Middle East fact-finding trip where he expects to "assess the peace process, the peace-keeping force in the Sinai, the autonomy talks and regional issues."

Would he be visiting there often, someone asked.

"It's been the habit of my predecessors to do so," he said.