Angered at themselves for letting the series go on as long as it did, the Philadelphia 76ers let loose all their might against the Milwaukee Bucks tonight.

The result was a convincing 115-103 victory at the Spectrum that sent the 76ers to the National Basketball Association championship finals for the third time in the last four seasons and the fourth time in the last seven. The last time the 76ers won the world title was in 1967.

The 76ers were dominant inside, outside and all over tonight. Andrew Toney had 30 points, Moses Malone 28 and 17 rebounds and Julius Erving 26 points, as the 76ers eliminated the Bucks, four games to one, in their best-of-seven Eastern Conference championship series.

They will now face the winner of the Los Angeles Lakers-San Antonio Spurs series for the NBA championship. The Lakers led that series, 3-1, going into last night's game at the Forum.

Milwaukee Coach Don Nelson is convinced that whoever the 76ers face will be nothing more than fodder, anyway.

"The 76ers are the best team I've seen in 10 years," said Nelson, "no question. They should be the next world champions. I can't see any team touching them. They just have everything. They have no missing links.

"We couldn't have done any better than we did. We had to play over our capabilities to just compete with them and they could play mediocre and still be in the game."

While the first four games of the series were defensive battles with the tempo dictated by the Bucks, Milwaukee decided to run with the 76ers tonight.

It still wasn't enough.

Malone, who wasn't double-teamed much tonight because the 76ers were running so well and because Toney was so deadly from outside, said he didn't want this to be a close game, "so we were more aggressive and looking to run all the time. Milwaukee made it easier by running with us."

Toney made his first five shots and had 20 points in the first half, but the Bucks always managed to find a way to stay within striking distance. They trailed by seven early in the game, but behind Marques Johnson's nine first-quarter points, cut the lead to two by the end of the period. They led by two points once in the second period, after a 22-foot jump shot by Junior Bridgeman (20 points) and a 16-footer by Bob Lanier, but that was the only time they led.

The 76ers quickly regained the lead on baskets by reserves Clint Richardson and Cleamon Johnson.

The Bucks trailed by only a point late in the half, but Toney scored on a length-of-the-floor drive and Erving on a fast break for a 59-54 halftime lead.

Marques Johnson (21 points) and Lanier (14) led a rally that got the Bucks within a point early in the third period. The 76ers responded with a 13-2 spurt, six of the points by Erving, all on the fast break, to increase the advantage to 12 points.

Malone, too, showed what kind of game he was having in that span. On one sequence, he blocked a shot by Lanier, then hurried upcourt fast enough to score on a fast break layup, get fouled and convert the three-point play.

Charlie Criss, the 5-foot-8 hero of Milwaukee's only victory of the series, scored eight points in the next four minutes and the Bucks reduced the margin to 81-76. But Maurice Cheeks made a free throw and then, after Johnson was called for a travelling violation, Richardson scored.

Richardson stole a pass from Sidney Moncrief and fed Cheeks for a fast break. Johnson missed two free throws for the Bucks and Malone scored with an offensive rebound for another 12-point lead and this time the Bucks couldn't recover.

The closest they came in the final period was seven points, but Toney scored four straight to take care of that little rally.

"We let the game get out of control in the second half when we let them get their fast break going," said Moncrief, who fouled out midway through the fourth period.