One of the world's foremost authorities on armored warfare claims that the US Army's new XM-1 tank is "just asking to have [its] turret knocked off by a well- placed shot."

According to Robert J. Icks, a retired Army colonel and author of numerous books on armored vehicles, the space between the hull and turret on the XM-1 "when the gun points forward would appear to be a perfect shot trap."

The Chrysler Corporation, maker of the XM-1, vigorously denies this assertion of vulnerability and the Army, buffeted by widespread criticism of the main battle tank in past months, declines to comment on the matter. "We don't see any useful purpose in discussing it," says a spokesman sourly.

Colonel Icks first made his "shot trap" allegation last December in the pages of National Defense, the journal of the American Defense Preparedness Association. Others have since endorsed his view. Writing to the magazine last June from Quebec, Gunter Scherrer, author of a forthcoming book on the World World II tank battle of Kursk, declared that he and a former German tank commander, who had destroyed 13 Russian tanks in one day in World War II, came to the conclusion that the XM-1 "would be a most desirable target for a good antitank gunner" after studying photographs and pictures of it.

In last month's issue of the magazine, a former Marine Corps warrant officer added his criticisms to the debate.

"The turret of the XM-1 is fraught with shot traps," declared Thomas Swearengen. "A single high explosive projectile trapped between the turret and the hull can readily remove the turret."

Reached at his home in Burton, S.C., Mr. Swearengen elaborated on his criticism of the XM-1. He claims that its glacis plate (the frontal part of the tank) "cannot absorb direct hits by high velocity projectiles nor can it withstand hits from HEAT [high explosive antitank shells.] It needs an angle of about 55 degrees to be able to deflect these rounds."

Calling the tank "a virtual death trap," Swearengen, who served in the Marine Corps as an explosive ordinance disposal (EOD) officer and who describes himself as "a student of explosive ordinance," urges an immediate redesign of the XM-1 to eliminate shot traps and provide maximum ballistic protection with sloped armor. He adds that no amount of British- designed Chobham armor, with which the tank is liberally equipped, "can help the XM-1 in its present configuration."

Faced with this latest barrage of criticism, Chrysler Corporation has issued a bold challenge to its antagonists. "I'd be prepared to have them shoot anything they can find at the XM-1, including the latest Eastern bloc weapons," exclaims Louis Felder, manager of the XM-1 engineering program in Detroit. "We've done that and we've done that more than once."

Mr. Felder dismisses changes that the XM-1 is replete with shot traps.

"These people just don't understand the design of the tank itself," he says. "In any tank design there are certain areas, nooks and crannies, that it is impossible to guard. But in this particular tank the design is such that I consider those nooks and crannies to be at an absolute minimum."

Responding to Swearengen's criticism of the XM-1's glacis, he says: "He's totally out of date. The concept of armor protection has changed radically over the last 10 to 15 years."

Felder sees no reasons whatever to change the design of the tank.

The XM-1 Abrams tank, named for Gen. Creighton Abrams, whose 37th tank battalion spearheaded the relief of Bastogne in 1944, has had a difficult birth. But the tank's major problem, dust ingestion by its turbine engine, which attracted so much attention last year, has been corrected, according to Percy Pierre, assistant secretary of the Army for research, development, and acquisition.

"The XM-1 is the best tank that has ever been built," he told Congress earlier this year. "The troops have been extremely pleased with the tank."

But the XM-1's turbine engine, never before put in a tank, still stirs controversy. Colonel Icks points out that it consumes much more fuel than a diesel engine and claims that it emits a "characteristic whine which gives away the fact that that kind of vehicle is in the vicinity."

Felder replies that the turbine is twice as powerful as the diesel in the M60 tank, which the XM-1 is replacing.

To date Chrysler Corporation has delivered 36 XM-1s to the Army out of a total order of 7,034. The tanks, which cost $1.4 million apiece, are to be deployed in Europe in the early 1980s.

But problems may still lie ahead for the XM-1. The new Soviet T-80 tank may well outclass it, say armor experts. Indeed, according to Dr. Pierre, NATO's antitank weapons cannot penetrate its frontal armor -- armor that may well owe much to Britain's revolutionary Chobham variety, samples of which, according to the London Daily Express, were smuggled out of West Germany by Soviet agents some years ago.

"The turret of the T-80, unlike the round turrets of the older Russian tanks, is angular and box-like to maximize the deflecting capabilities of the armor and shows the influence of Britain's Chobham-armored Chieftain tank," notes George Custance in National Defense.

But Felder stoutly defends the XM-1, claiming it is superior to West Germany's Leopard II and to Britain's new Challenger. In Colonel Icks's view, the British Chieftain is the best tank in the world today, "although it's a little bit overheavy."

The best tank ever made, he says, was the German Panther of World War II "because the glacis was at such an angle that a shot deflected from it would also be deflected from the front face of the turret. It was almost a continuation of the same line. That feature has been lost sight of these days."