The chairman of the House Armed Services Committee yesterday joined in blasting President Reagan's plan to put the new MX missile in rebuilt Titan missile silos rather than to keep it moving among a number of shelters to protect it from attack.

"We are back to the beginning in the modernization" of the U.S. land-based missiles, Chairman Melvin Price (D-Ill.) complained to Defense Secretary Caspar W. Weinberger and other Pentagon officials sitting at the committee witness table.

Price's attack came a day after Chairman John G. Tower (D-Tex.) of the Senate Armed Services Committee also condemned the MX part of Reagan's strategic blueprint. Other influential members of Congress usually supportive of the Pentagon have also attacked the MX proposal. Since the Armed Services committees are the ones that must authorize the money needed to put the first 36 of 100 MX missiles in Titan silos, the outlook for Reagan's new basing scheme is at least stormy.

Reagan's basing scheme "has even more uncertainties than the direction that has been rejected," Price said. He said the committee will conduct hearings to see what military commanders and weapons specialists think of it.

Former President Carter intended, with Congress' blessing, to move the MX around on the valley floors of Nevada and Utah to reduce the missile's vulnerability to surprise attack. Weinberger said that plan's fatal flaw was that the Soviet gunners could keep all the MX garages covered with warheads, even if 4,600 shelters were built as the Air Force recommended.

Weinberger said under Reagan's plan the Titan silos will wrap enough concrete and steel around the MX to withstand a blast exerting up to 5,000 pounds of pressure per square inch, compared with 2,000 pounds per square inch for existing Minuteman silos. This hardening will cost up to $20 million a Titan silo, according to the Pentagon.

Price considers this a losing proposition, given the steadily increasing accuracy of Soviet warheads. Said the House committee chairman:

"No evidence available to date indicates that hardening a limited number of silos will provide any significant added survivability in the face of the increasing accuracy of Soviet strategic missiles."

Price had kinder words for Reagan's decision to produce 100 B1 bombers but said it may now be too late to convince Congress to go along. "Its approval by the full Congress at this time is by no means certain," he said.

Weinberger over two days of contentious congressional hearings has stressed that the hardened-silo scheme for the MX will buy a few years of reduced vulnerability while adding to the U.S. offense of land missiles. Other MX basing options will be studied in the meantime, with the decision point 1984, he promised.

Rep. William L. Dickinson of Alabama, ranking Republican on the House Armed Services Committee, said yesterday he "heartily" supported Reagan's B1 decision but doubted wheter burying MX under tons of concrete and steel would reduce the missile's vulnerability "given the accuracy and megatonnage of Soviet ICBMs."

Rep. Samuel S. Stratton (D-N.Y.) regretted that Reagan had rejected the mobile MX option the Pentagon's Joint Chiefs of Staff had recommended and failed to consult them on the details of his six-year strategic plan before it was announced on Friday.

Gen. David C. Jones, chairman of the Joint Chiefs of Staff, confirmed for Stratton that the chiefs had recommended a different MX basing scheme and said he was "reserving judgment" on whether hardening Titan silos would be worth the cost.

However, Jones applauded Reagan's strategic blueprint as a whole. Besides building 100 MX missiles and 100 B1 bombers, it calls for strengthening the command and control systems for nuclear war; improving the air defense of the United States; going ahead with the Trident D5 silo-busting missile for submarines, and putting nuclear missiles in the nose of Los Angeles-class attack subs.

"I can back the program with enthusiasm," said Jones of what he called the "overall program" for upgrading the nation's strategic forces between now and 1987. The Pentagon estimates the six-year cost at $180.3 billion in fiscal 1982 dollars and $222 billion if administration future inflation estimates are added.

The Joint Chiefs--comprised of a chairman and the heads of the Army, Navy, Air Force and Marine Corps--have not openly rebelled against civilian decisions in recent history. They disagreed with many of President Johnson's Vietnam war decisions, such as his rejecting military pleas to call up the reserves and his limiting the bombing of North Vietnam, but not one of them resigned during that long war. The chiefs during Carter's term also endorsed the SALT II arms control treaty Reagan has assailed.