Clarence (Butch) Bailey told a jury yesterday how at the age of 15 he became a guard for an alleged narcotics operation in Northwest Washington that grossed $20,000 a day.

"I was told if someone came in to rob the place I was to shoot them," said Bailey, who is still 15.

His armament, he said, included a .357 magnum pistol, a .32 automotic pistol, "which didn't work," a .38 police special revolver, "which I didn't think that it would work either," and "a full-length 12-gauge shotgun."

Bailey described his weapons' and duties during his testimony for the prosecution in the trial in U.S. District Court of Calvin Agurs, 28, also known as Sykes, the alleged leader of the narcotics ring.

He said he got $200 "every week, or every two or three days" for his work, which involved keeping watch at an apartment in the 1300 block of Euclid Street NW and at a second in the 1800 block of Verman Street NW. Bailey told the court that he himself was not an addict.

According to other witnesses, the operation moved to the 1700 block of Seaton Street after last Nov. 12, when four persons died and 33 other customers were hospitalized after taking super-strength doses of the brown "Mexican mud" heroin the ring was distributing.

He was at Vernon Street, Bailey said, the only time he ever shot anyone. He said he accidentally killed the girl friend of one of his coworkers while showing her one of his pistols. He was convicted in juvenile court of carrying a dangerous weapon as a result of that incident.

For Assistant U.S. Attorney Roger Adelman, the presecutor, the crucial question for Butch Bailey was whether he had ever seen Agurs in the course of his duties. This is because Agurs operated in the background much of the time, according to other witnesses, and the government's case turns on whether it can tie him into the drug dealings.

Agurs was indicated with 17 other persons on charges of conspiracy to violate federal narcotics laws and violation of several of these laws. All 18 were scheduled to go on trial together. Last week, however, charges against two of the defendants were dropped, seven others pleaded guilty to conspiracy, and the remaining eight were severed from the case to receive their own trials.

Butch Bailey told Adelman that he had seen Agurs, whom he said he knew as Sykes, on two occassions. He said he met him on the day his coworker's girl friend was shot, and a second time when some money was missing from one of the apartments where narcotics allegedly were being sold.

On cross-examination, Kenneth Robinson, Agurs defense attorney, brough out the fact that Bailey had refused to testify at all during pretrial stages of the proceeding two weeks ago. For the refusal, Chief Judge William B. Bryant, who is presiding at the trial, sentenced him to 90 days for contempt of court.

Bailey agreed with Robinson, yesterday that he had told Judge Bryant two weeks ago that "I ain't scared of nobody."

He testified yesterday that he was scared of "Sykes, (Agurs) being that I'm testifying against him, he might try to see me hurt."

Robinson asked when he had changed his mind about taking the witness stand for the government. Bailey said he had thought about it and decided that "Sykes" alleged organization had not given him sufficient support following the shooting incident.

"He got all this money," he told the jury, "and when I had this beef down here they didn't send me no lawyer or nothing, and I was supposed to be an employee."

Bailey said he became a guard for the organization after he had been "recommended" to one Joseph H. King Jr. He said King, who pleaded guilty to conspiracy in the case last week, asked if he had "heart."

"I told him I had heart depending what he had in mind," Bailey testified.

In other testimony yesterday, Dept. Charles L. Marcum of the metropolitan police narcotics branch, described how he had used the roof of the garage of third district police headquarters at 1620 V. St. NW as a vantage point from which to observe alleged narcotics activity in the 1700 block of Seaton Street NW.