Three Marine drill instructors lined up 150 recruits under their command at Camp Pendleton, Calif., last week and systematically beat more than 100 of them, Corps officials acknowledged yesterday.

The drill instructors, Marine sources said, ordered two platoons of recruits out of their beds in the early morning hours of June 26, told them to line up and then went down the line punching, kicking and slapping the young trainees.

The apparent object of roughing up 116 recruits, sources said, was to settle an argument amoung the drill instructors over which of two platoons housed together in a Camp Pendleton barracks was tougher. The drill instructors had been drinking, sources said.

A fourth drill instructor may be court-martialed for failing to report the incident, the Marine Corps said.

None of the recruits was seriously injured, according to a Marine spokesman at the San Diego boot camp, home base for the recruits who were taking rifle training at Camp Pendleton.

Marine regulations forbid drill instructors from manhandling recruits in any way. The Corps overhauled its training in hopes of ending abuses in the wake of the fatal beating of Lynn [Bubba] McClure at the San Diego boot camp on December 6, 1975.

The four drill instructors have been suspended from duty. An investigation will determine if there are grounds for court-martialing them.

Marine officials queried yesterday could not recall any previous case where so many recruits were abused at one time.

In a separate incident at the boot camp on Thursday, a drill instructor allegedly punched recruits under his command. He punched 14 recruits in the course of several days last month, a Marine spokesman said, and is being held for special court-martial.

"This is a hell of a welcome aborad," Gen. Robert H. Barrow, who became Marine Corps commandant on Sunday, said yesterday. Barrow and Maj. Gen. Richard C. Schulze, commander of the San Diego boot camp, were at the forefront of those officers the previous commandant assigned to reform recruit training.

Barrow said in an interview he could not speak about the cases under investigation, but added that drill instructors who abuse recruits undermine the whold rdform effort of the last several years.

"I know of notheing I deplore more" than drill instructors abusing recruits in their charge, Barrow said in an interview yesterday. "It's like sticking me with a hot poker.

"At one time the DIS [drill instructors] would have thrown up their protective association" when one of their own got in trouble for mistreating recruits, said the commandant.

This time, continued Barrow, the DIS at San Diego "are mad sa hell" about the alleged mistreatment of 116 recruits by the three men. This represents "an attitudinal change."

Barrow said such a change does not excuse even isolated case of mistreatment, especially since today's drill instructors "all have been hand-picked and have plenty of supervision" and thus are professionsls.

"I'm very unforgiving when a professional does something unacceptable," Barrow said, adding that the Corps is conducting "an investigation of this whole business" at San Diego.