The gunfire that wounded President Reagan outside the Washington Hilton a year ago today has left a subtle but significant imprint on the man and his presidency.

While Reagan rarely discusses the incident, aides and intimates say that what one of them calls the president's "sense of mission" was heightened by the attempt on his life.

"He realized that he had become president to accomplish something and that he has a limited time to make his impact felt," the aide said.

Many supporters of Reagan believe that the shooting also had an effect on his wife, Nancy, who is said no longer to want her husband to seek a second term in office. The Reagans have never discussed this publicly, but one story which has been frequently repeated in Republican circles is that the president has promised his wife that he will not run again in 1984.

By any measurement, Reagan is a more insulated president than he was before the shooting. Security is tighter. The president often wears a bulletproof vest when he goes out in crowds. Reporters have fewer opportunities to ask questions, and citizens fewer chances to meet with him.

Although Reagan remains friendly and outgoing and makes as many speeches outside the White House as he did before the assassination attempt, he is no longer free to move spontaneously into crowds as he used to do when governor of California and as a presidential candidate in 1976 and 1980. His only public appearances among ordinary citizens are unannounced ones, such as his flight to Fort Wayne, Ind., earlier this month, where he briefly assisted volunteers who were stacking sandbags to hold back flood waters.

Reagan is kept far away from demonstrators who gather to protest his policies. As a result, some close to him think that one result of the shooting has been to diminish his awareness of growing opposition to some of his policies.

The president's public comments on the shooting have usually been jocular. Asked last year by the Washington Star what he would have done differently in 1981, the president said: "I wouldn't have gone to the Hilton."

But Reagan returned to the hotel yesterday, one year less one day after he had been struck by a gunman's .22 caliber bullet which ricocheted off his limousine and lodged in his lung. White House press secretary James S. Brady was seriously wounded by another bullet. Secret Service agent Timothy J. McCarthy and Washington policeman Thomas K. Delahanty, both of whom have since recovered, also were wounded.

John W. Hinckley Jr., a 26-year-old drifter who was arrested within moments of the shooting, is in a military stockade still awaiting trial in the assassination attempt.

The scene at the Hilton yesterday contrasted in almost every way with the one a year ago, a gray, drizzly Monday when Reagan went to the hotel to address the building trades department of the AFL-CIO. Leaving the hotel through a side door onto T Street, the president paused a split second on the sidewalk in response to the shout of a wire service reporter who wanted to ask him about labor unrest in Poland.

In that moment the gunman fired from among a crowd of spectators and cameramen who had gathered in front of the lower lobby entrance of the hotel for a glimpse of the president.

Yesterday was bright and sunny, and there were few spectators as the president arrived to address the National Association of Realtors. Police cars blockaded the side streets. Reagan, who has visited the hotel several times since the assassination attempt, made no reference to the shooting in his speech.

When he departed, he left through the garage, and the pool of reporters who accompany him was kept far away.

This has been the usual pattern since Reagan's recovery, which means that reporters have far fewer opportunities than before to ask the president questions on the run. Since last October, however, Reagan has been holding monthly press conferences, and he will have another one Wednesday night.

A year ago the Academy Awards ceremony was postponed and the national collegiate basketball championship game was played with little notice because of the shooting attempt. This year Reagan postponed his press conference so that it would not compete with the game or the awards ceremony.

Some close to Reagan believe that the shooting caused Reagan to focus exclusively on his economic agenda during his long recovery last year and delayed the development of administration foreign policy initiatives. What is incontestable is that the assassination attempt for a long period gave more authority and influence to the White House trio of advisers--chief of staff James A. Baker III, deputy chief of staff Michael K. Deaver and counselor Edwin Meese--who dominated administration policy last year.

The personal effect on Reagan of the shooting is more difficult to define.

The president is a religious man who usually keeps his feelings to himself. He has rarely discussed the shooting with outsiders. However, on Good Friday (April 17) in 1981, he commented to Cardinal Terence Cooke, the Roman Catholic archbishop of New York, who visited the president in the White House while he was recuperating.

"The hand of God was upon you," Cooke said.

"I know," Reagan replied. "And whatever time he's left for me is his."