To get to the bar last night at the Corcoran Gallery, visitors had to walk past a buffalo hunt, a snow-covered boulder with a bear behind it, bands of outlaws and Indians, and a pack of four hard-riding cowboys out for a night on the town, who held their six-shooters high above their heads and pumped lead into the Western sky. Fortunately for the museum's peace and quiet, these were all paintings or sculptures, part of the current exhibit, "The American West," the openings of which was being celebrated at a party for a blue-ribbon guest list of about 200.

The Corcoran's director, Peter Marzio, stood at the foot of the broad marble staircase in the museum's atrium, directing the formally clad guests: "Up the stairs; follow those people up and turn right, and after you go through the exhibit you'll be rewarded with a drink."

Many of the guests took a long time getting to the bar, which was reached by coming down the back stairs after the exhibit. Bureaucrats in black ties gazed for a long time at scenes of bronco-busting and running gunfights and horseback, Indian dancers and vast open landscapes. Interior Secretary James Watt saw in the exhibit "the spirit of the American West" that has brought to town by the Reagan administration. "This is the picture of rugged individualism," he said, "in all its beauty and grandeur."

A Western spirit did pervade the evening, with a high proportion of guests from Colorado, the home of oil and gas executive Philip Anschutz, whose private collection provided somewhat more than half the 55 items in the exhibit. Virtually all of the Colorado congressional delegation was present, as well as Supreme Court Justice Byron White, a Colorado native, and a substantial delegation from the Cabinet, the White House staff, and the House and Senate.

"My wife usually has a great problem getting me to turn out for art openings," said Anschutz. But in spite of a case of flu that had sent his temperature to 102, he managed to attend the party in honor of his collection, which Marzio called "in my opinion, the finest collection of Western art that is now in private hands."

"We were very glad to be able to display this material," another member of the Corcoran staff said, "because it will help call attention to our own collection." Before the collection leaves the Corcoran, a friend predicted to Marzio, "You may have lines stretching all the way down the street to the White House." "I can accept that," Marzio said calmly.

Anschutz began collecting Western art around 1960 -- when, he recalls, it was a lot easier to find than it is now. "I think the period of collecting Western art has about come to an end," he said."There isn't much available now, what with the demand from museums and other private collectors. From 1960 to 1970, it was different; then around 1970 it began to change, and the biggest change has been in the last three years." He said he thinks a counterfeit market may be starting to grow. "I know I've seen counterfeit bronzes, and some of them were damned good. I can't prove that I've seen any counterfeit paintings."

After the Corcoran, the Anschutz pieces -- along with other items that Anschutz owns -- will make an international tour of such cities as Brussels, Peking, Canton, Berling, London, Edinburgh, Paris and Vienna, with various corporations picking up the expenses -- ITT, for example, in Brussels, where it has its European headquarters. "This kind of art is very popular in Europe," said one connoisseur at the party. "Over there, they think anybody can paint a still life, but it takes and American to do a buffalo hunt."