Though President Carter succeeded in killing the B1 Bomber, he is encountering serious congressional resistance in putting a halt to production of the nuclear bomb - the B77 - that was custom-designed for the plane.

The Carter decision, according to administration officals, is expected to save hundreds of millions of dollars. And, with proposed modifications of an existing nuclear bomb, the Air Force will get a comparable weapon for the slower-flying aircraft it already has.

But the House Armed Services Committee and some officials in the government's nuclear weapons community are working to get Congress to reverse the president's decision and have the B77 built even without a B1 to carry it.

Called the full fuzing option bomb, or FUFO, the B77 was designed to be dropped by a B1 flying at about 200 feet and more than 700 miles per hour.

So that the low-flying plane could get away before its released nuclear weapon exploded, the B77 has a special insensitive high explosive that would not detonate when released even if the bomb slammed into a concrete building at that high speed. The bomb's fuzing, firing and timing systems are so well protected that they, too, would still function after hitting objects on the ground.

The B77, as with other bombs in the U.S. stockpile, has several yields that can be set with a dial on the weapon. The exact numbers are classified, but since it was scheduled for a strategic mission, some yields are probably in the 100-kiloton-or-more range. The bomb dropped on Hiroshima in 1945 was 12.5 kilotons.

More than $150 million has been spent on developing and testing the B77, according to government officials. Another $100 million or more in development money will be spent this year and next.

Carter, however, decided late last year that he did not want to go ahead with production of the B77.

Instead, he settled on the continued research program along with putting some funds into providing better safety devices on nuclear bombs already deployed.

Carter's decision was made by his Office of Management and Budget, not the Department of Energy, which builds nuclear weapons.

Particularly disappointed by the president's move was DOE's Lawrence Livermore Laboratory in California, the nuclear weapons development site that designed and was developing the B77.

Its rival government weapons lab at Lost Alamos, N.M., fathered the B61 bomb, the newest weapon now in the nuclear bomb stockpile.

Another person who disapproved of Carter's decision was Seymour Shwiller, a former Air Force officer who since the 1950s has worked in the government's atomic weapons program. Shwiller, however, is one Department of Energy employe who could openly attack Carter's plan.

That is because for the past two years Shwiller has been the chief nuclear weapons expert on the House Armed Services Committee staff. Though he works for a congressional committee, Shwiller is still on DOE's payroll.

Armed Services Chairman Melvin Price (D-Ill.) approved the unusual situation because he wanted Shwiller on his staff and Shwiller wanted to keep his retirement benefits built up at the government agency and its predecessors.

Shwiller's situation is "undesirable," Rep. M. Robert Carr (D-Mich.) said yesterday, but added that it was the only way Pric could get him for the committee staff.

When DOE officials came up to the Armed Services Committee in January and February to explain the Carter proposal in closed hearings, it was Shwiller who attacked it.

He made the point that even with the B1 gone, the B77 bomb was needed for the B52, the F111 and other Air Force and Navy tactical fighter-bombers.

According to Carr, Shwiller argued that the OMB analysis that money would be saved by scrapping production of the B77 Left out the fact that money would be regained from the enriched uranium recovered from the older bombs that the B77 would would replace.

For Carr, Shwiller's opposition to the DOE presentation was "proof positive there was not a conflict, that he was working in favor of the committee."

But a congressional aide, who asked not to be identified disagreed.

"The old [Atomic Energy Commission] and lab bureaucracy which Shwiller represents wants to reverse the president's position," he said, "And that is what he is doing."

Repeated attempts to contact Shwiller were unsuccessful.

A colleague on the Armed Services Committee, Adam Klein, would not discuss what the committee was doing in its executive sessions.

Administration officials expect that Price's committee will put funds for producing the B77 into the fiscal 1979 authorization bill and attempt to push it through Congress.

Because the new bomb's production costs are classified, the White House has not made public just how much money actually could be saved by going its route rather than the committee's.

Before the battle is over, however, details on the B77 and its costs are expected to come out as the nuclear weapons establishment attempts to save one of its programs.

"What's involved here," one congressional aide said recently, "is an effort to put a stop to the system that has fueled nuclear weapons building in the past - the labs pushing the military, and the Congress approving."

The real question, according this aide, should be whether additional bombs are needed, not whether the B77ought to be built just because it is new.