About 50 District correctional officers picketed the D.C. Jail yesterday, complaining about overcrowding, understaffing, inadequate pay and the proposed disciplinary action against an officer accused of using "excessive force" on an inmate.

"This is a peaceful protest, but we can't guarantee what will happen in the future. The D.C. Jail is a powder keg waiting to explode," guards' union spokesman Johnie W. Lee shouted through a bullhorn as uniformed officers marched with picket signs and yelled slogans.

The demonstrators, members of Local 1550 of the American Federation of Government Employees, are inviting Mayor Marion Barry to "lunch at the jail . . . so he can feel the tension, hear the noise level and see the abuse we work with every day," Lee said.

The protest was sparked by longstanding complaints about jail conditions, but also by the proposed discipline ordered last week against Walter Elmore, a veteran officer who faces charges in a Jan. 4 fight with an inmate.

AFGE officials alleged that Elmore was defending himself against an assault by an inmate, but that Department of Corrections officials have accepted the inmate's version of the incident rather than Elmore's.

"You defend yourself, and you end up getting sent before the U.S. attorney," Elmore said, but declined to discuss the incident further. Department officials could not be reached for comment.

"This administration takes the word of the inmates, not the officers," said AFGE representative Rene Dubose, "The officers don't get respect."

"Four years ago, officers walked out of this jail," Dubose said, referring to a two-day strike in 1980. "And I would venture to say that it will happen again if things don't change quickly."

AFGE -- which faces a challenge from a competing union, the Fraternal Order of Police, in a Feb. 19 election among 2,000 corrections employes -- pledged to lobby both in Congress and the City Council for increased funding for staff, training, and pay parity with police, a major goal of corrections officers.

The jail, in Southeast near Robert F. Kennedy Stadium, has nearly 1,000 more inmates than its intended capacity.

District and federal officials are considering plans to build more space.