The D.C. police department began issuing "hollow nose" ammunition yesterday to its 4,300 officers to replace conventional round-nose bullets that have been used in the past.

The move implements a controversial policy announced last November by Police Chief Maurice J. Cullinane. The change has been approved by the police department's citizens advisory panel and the policeman's union and has been opposed on humanitarian grounds by the American Civil Liberties Union and other groups.

In its announcement in November, the department said the change would give officers a weapon with more "stopping power" than that provided by round-nose bullets but would not cause more serious wounds.

It said hollow-point bullets expand when they strike, expending more of their energy at the point of impact than round-nose bullets. This increases their stopping power but not wounding power, the department said.

Dr. Vincent J. M. DiMaio, deputy medical examiner of Dallas County, Tex., and a recognized expert in the field, says it is impossible to distinguish a wound caused by a hollow-point bullet from one caused by a round-nose bullet until the bullet is retrieved.

DiMaio says hollow points are frequently and erroneously confused with Dum Dum bullets. Dum Dums, named for a town in India, can cause massive tissue damage far from their path through a body because of their extremely high velocity.

Bullets now being issued by the police department have much slower velocities and do not cause such damage, experts say.

Ralph Temple, head of the ACLU's Washington office, has said: "I just do not believe that a bullet that is going to stop someone faster does not have greater wounding power."