FOR MORE than a decade, Congress and a variety of criminal-justice experts have been working on a massive revision of criminal sentencing in federal courts. On Nov. 1, a completely new sentencing system that will include changes in procedures and penalties for every single federal crime will go into effect. At this late date, though, many of the people who are to carry out the changes are beginning to get cold feet.

The idea behind sentence guidelines is to reduce disparity in penalties by setting objective standards for judges to use in devising sentences. In 1984 Congress created a Sentencing Commission, which was given responsibility for identifying all the factors that should be weighed at sentencing, assigning values to these factors and setting out specific sentences for each crime in the code. Rigid timetables in the statute govern the work of the commission and the putting into effect of its recommendations. Members of the commission are all experts -- some are senior federal judges -- but the work went slowly. There was a long delay in naming commission members, which necessitated the postponement of all deadlines by a year. And the subject was both complicated and controversial.

Six months ago the guidelines were sent to Congress, set to be inaugurated Nov. 1, but at that time the commission itself asked for an additional nine-month delay. The House, however, on a record vote earlier this month, refused to go along, and now the Senate Judiciary Committee is working only on a few last-minute technical amendments. There is little chance for further delay in spite of the fact that federal judges, from Chief Justice Rehnquist on down, are adamant about the need for more time to study the guidelines, try them out informally and suggest changes.

In the past six months, the Sentencing Commission has provided training programs for most of the probation officers in federal courts, and seminars are scheduled for the judges next month. There will be a little lag time, since the new sentences will be used only in cases involving crimes committed after Nov. 1. No one expects the changeover to be accomplished without problems, but they can be handled.

As part of the plan, parole has been abolished, and criminals will be sentenced to fixed terms. This may increase the prison population, so these figures must be watched closely. Judges may also find that in certain situations their discretion is so restricted as to hamper the dispensation of justice. But the Sentencing Commission is a permanent body, and its members will continually monitor the use of the guidelines. Fine-tuning is expected, and even major changes are possible if Congress is convinced that some aspect of the new program is not working.

Some public officials are enthusiastic about the guidelines because they foresee tougher sentences and less room for judges they regard as "soft" to control the sentencing process. On the other side, defense lawyers in particular fear the new program will lock in long prison sentences and discourage the use of other penalties that don't involve incarceration. Congress, however, did not intend to curb lenient judges or to mandate harsh penalties across the board, but to make all sentences more predictable and more equitable. That is what took so long to plan, and that is what is expected to be accomplished when the federal criminal justice system enters a new era next month.