Rep. James M. Shannon (D-Mass.) charged yesterday that the Reagan administration had speeded up reviews of Social Security disability cases so recklessly in order to chop the federal budget that projected five-year savings are now estimated at $4.9 billion instead of the $400 million estimated in 1980.

Shannon gave the figures, based on Social Security Administration data and included in a Congressional Research Service study, as witnesses before a House Social Security subcommittee berated the SSA for the procedures it used in ordering 400,000 people off the disability rolls in the past two years.

Reviews of the rolls were mandated by Congress in 1980 but subcommittee Chairman J.J. (Jake) Pickle (D-Tex.) said yesterday there had been "hasty and harsh implementation."

He promised to get legislation through the House before the August recess to spell out the exact procedures Congress wants used from now on.

Paul B. Simmons, deputy Social Security commissioner, responded that the speedup and the larger estimates resulted from SSA and General Accounting Office findings that as many as 20 percent of the people on the rolls are capable of work.

He also defended the administration's record, citing a long list of recent actions easing procedures.

The impending Pickle bill is expected to focus on these questions:

* Should the SSA be barred from removing a person unless his or her medical condition has improved?

* Should Congress require a substantial increase in personnel and training?

* Should Congress beef up SSA plans for more face-to-face hearings with recipients and require them at an earlier stage in the review?

* When the SSA loses a case in federal court, must it apply the precedent to everyone with similar claims or may it continue limiting the ruling to the specific case?

* Should Congress require a rewriting of mental health rules, which the American Psychiatric Association said were based on outdated classifications and health notions?

* Should a provision allowing people ordered off the rolls to continue getting benefits during their appeals be extended after it expires in October?