The backroom battle on Capitol Hill over medium-range anti-tank weaponry is one of those rare ones in which pork-barrel politics plays less of a role than principle -- in this case, the safe- ty and fighting effectiveness of infantrymen in bat- tle.

But that does not mean that there is any less at stake for the interested contractors, or that the prestige of individual members of Congress is not on the line.

The immediate issue is whether the Army

conducts a competitive test of its Dragon II infantry anti-tank missile against two foreign-made alternatives, Sweden's Bofors BILL missile and the French-German Milan 2. Until recently, the Army had been resisting.

The Army wants to continue developing a sophisticated new-generation anti-tank weapon called AAWS-M, and fears that a test of the Dragon II would show that the Bofors BILL and Milan 2 are superior weapons which the Pentagon could deploy quickly to U.S. Army and Marine infantry divisions. Army and congressional supporters of the advanced missile fear that if such a deployment occurs, pressure will rise to postpone or kill the new-generation anti-tank device to save money.

But the House Armed Services Committee's Rep. Charles E. Bennett (D-Fla.), a World War II infantryman, thinks the Dragon II is a dangerously inferior weapon that should be exposed immediately through this competitive test. Aides say Bennett has no faith in the Dragon II even though the warhead is made by McDonnell Douglas Corp. near his home district in north Florida.

The most passionate House advocate of the AAWS-M is also a former infantryman -- Rep. Les AuCoin (D-Ore.), a member of the Appropriations defense subcommittee. He has been opposing the competitive test of the Dragon II against its European rivals because, like the Army, he fears the test results could be used as an excuse to deploy one of the European weapons, and postpone or kill the AAWS-M.

AAWS-M, which stands for Anti-Armor Weapons System-Medium, is being developed by Texas Instruments Inc. and Martin Marietta Corp. AuCoin's advocacy has caused some to wonder what is in it for him. In 1988 he received a $1,000 honorarium from Texas Instruments. But AuCoin has written Defense Secretary Richard B. Cheney an unusual letter that said in part: "My only preference is that subcontracts {for the AAWS-M} not be placed in Oregon so that I can continue to deal with this program without parochial complications."

A key actor in this drama is Robert M. Sherman, author of more than 30 articles on defense and arms control, who first became interested in a new- generation "tank breaker" being developed by the Defense Department while working for Rep. Thomas J. Downey (D-N.Y.) in the early 1980s. When he switched to AuCoin's staff, he had no trouble interesting the former infantryman. AuCoin soon emerged as the most persistent House spur to the Army's development of a light missile capable of destroying heavily armored enemy tanks without exposing the attacker. In 1989, the Army chose the Texas Instruments system over two others.

The existing, wire-guided Dragon system forced the attacking infantryman to hold his sights on the tank until impact. The new system allowed the attacker to "fire and forget" -- to head for cover as the missile homed in on the vulnerable top of the targeted tank, using sophisticated software and the tank's infrared heat emissions.

In pushing for the test of Dragon II and its European competitors, Bennett is backed by other key defense Democrats, including Reps. Charles Wilson and Marvin Leath of Texas, George "Buddy" Darden (Ga.) and Dave McCurdy (Okla.). All reportedly like AAWS-M, but disagree with AuCoin that Dragon II should be continued in service until AAWS-M can be proven. That, they say, would jeopardize infantry lives if war erupts.

Recently, they have been getting tough. At a meeting with Lt. Gen. Donald S. Pihl, in the office of the assistant secretary of the Army for research, development and acquisition, they demanded that the service test the Dragon II side-by-side with Bofors BILL and Milan 2 as required by the 1990 defense authorization act.

The foreign arms makers have been pushing too. In April 1989, Sweden's Bofors hired the Alexandria, Va., lobbying firm of former congressman Bo Ginn (D-Ga.) to press the issue on Capitol Hill, paying a retainer of $10,000 every three months. Ginn is a former member of the House Appropriations defense subcommittee. His partner, William H. Edington, was Ginn's personal staff member on appropriations, and has made the rounds showing a video of the Bofors BILL in action. Edington has made campaign contributions to members of House defense committees and has attended fund-raisers for them.

Rockwell International Corp., also represented

by the Ginn firm, has an agreement with Bofors

to produce the missile in this country if Congress decides to buy it as an interim weapon before AAWS-M. AAWS-M is to be ready by 1993 at the earliest.

On the Senate side, the Army's opposition to a test of Dragon II has been taken up by Romie L. Brownlee, deputy minority staff director of the Armed Services Committee. His boss, Sen. John W. Warner (R-Va.), turned the issue over to Brownlee, a retired Army officer, who once commanded a mechanized infantry battalion that was equipped with the Dragon.

Brownlee argues that Bofors BILL is too heavy and too costly an alternative to Dragon II.

But those who take the Army's side in this dispute are caught in the position of supporting a dubious weapon. A Congressional Research Service study said the Dragon II warhead could not penetrate Soviet armor, and scored only one kill in 17 firings. It quoted estimates of the Institute for Defense Analyses that the casualty rate for Dragon gunners operating in European battlefield conditions "would be between 25 and 33 percent." The Defense Department's office of Operational Test and Evaluation has identified the Bofors BILL as a more effective weapon than the Dragon II.

It was this finding that resulted in language in

the defense authorization act approved last fall mandating a side-by-side test of the three systems. But the test still has not occurred; it remains hung up in bureaucratic maneuvering involving Congress, the Pentagon and the Office of Management and Budget.

The Players: Rep. Charles E. Bennett (D-Fla.), Rep. Les AuCoin (D-Ore.).

The Contractors: Bofors, Sweden; Aerospatiale, France; Messerschmidt-Boelkow-Blohm, Germany; Texas Instruments; Martin Marietta.

Lobbyist: Ginn, Edington, Moore & Made, Alexandria.