U.S. Customs agents are investigating Alexandria arms dealer Samuel Cummings for the way his company, Interarms, has been marketing one of the world's most famous guns, the Walther pistol.

The agents are trying to determine whether Cummings, a former Central Intelligence Agency employe who calls himself the "leading {arms} trader in the world," has traded on the famous Walther name and its German origins in a way that has misled customers.

The Walther, which is prized by gun collectors, has an almost legendary history: Adolf Hitler committed suicide with one, and a Walther was the weapon of choice for fictional secret agent James Bond.

According to sources, the Customs Service is investigating whether Cummings and his firm violated U.S. laws that require imported products to be labeled with their correct country of origin. Interarms, as the exclusive Walther agent in the United States, has sold millions of dollars worth of Walther pistols stamped "made in Germany," although they were assembled in France and then sent to West Germany for safety testing before shipment to the United States.

In an interview, Cummings confirmed that he has imported hundreds of thousands of Walthers since the mid-1950s that were assembled by a French firm called Manurhin under a licensing agreement with the Walther company of West Germany.

That agreement goes back to the days following World War II when Germany was prohibited from manufacturing and exporting arms. Walther then turned to Manurhin so the pistol could still be made, and their relationship continued after the prohibition ended some years later.

But Cummings denied that he ever attempted to mislead his customers, and he sharply criticized the Customs probe. He said he has battled with Customs officials in the past over interpretations of Customs law.

"We sold them {the pistols} for what we bought them as -- German pistols, made in Germany," Cummings said. "If you were a gun bug and came in and said, 'Look, isn't the frame and slide made in France by Manurhin?' we would have certainly said, 'Of course it is, but it's sent to Germany for final finishing.' "

Edward Ezell, the curator of the Division of Armed Forces History at the Smithsonian Institute's Museum of American History and a former Cummings employe, said Walther pistols are favorite items among gun collectors, police officers and citizens who keep guns. Sophisticated collectors may pay more for a Walther stamped "Made in Germany" than a pistol without the Walther name made in France, Ezell said.

A local gun dealer said the retail price range today for a German-made post-World War II Walther pistol is $700 to $1,200, while a comparable French-made gun would cost $400 to $700.

Cummings, who does a reported $80 million arms business worldwide, has been outspoken on subjects relating to the arms trade. Last month, in an interview on CBS's "60 Minutes," Cummings said Interarms could have carried out the Iran arms operation with far greater success than was accomplished by what he called the "hustlers" employed by the Reagan administration.

Customs officials won't comment about the investigation of Cummings or Interarms. In general, they said, "marking violations," if proven, may draw criminal or civil penalties. Customs may, for example, levy a 10 percent duty on the appraised value of improperly marked products. Customs law experts said marking cases may hinge on highly technical interpretations of where a product is "substantially" manufactured or altered.

Cummings said he had been interviewed by Customs agents as recently as four weeks ago. Agents also interviewed Manurhin and Walther representatives in Europe, according to sources. Cummings said he was told by investigators that Customs may seek to penalize him for his Walther imports since 1983. Estimating that figure at 70,000 guns, Cummings said a 10 percent levy would result in a fine of about $280,000.

Researcher Ferman Patterson contributed to this report.