The Army is now estimating the cost of a single Copperhead laser-guided artillery shell at $65,806, up 117 percent in calendar 1982.

Although the Army attributed the increase in the per-shell costs to sharp cutbacks in planned production, the new figures may doom the troubled $673.2 million program, for which Martin Marietta Aerospace is the prime contractor.

Rep. Dave McCurdy (D-Okla.) of the House Armed Services subcommittee on procurement said yesterday that he will seek to kill the program. "I personally think that if the Army doesn't recommend killing it, Congress will," he told a reporter.

Originally, the Army intended to build 133,058 of the shells at a cost per shell of $9,323, according to a 1975 estimate. The Copperhead was designed as a "smart" projectile, homing in on the reflection from a laser beam projected at the target by an infantry soldier or a remote spotter.

But the projectile has steadily lost support in Congress as its costs have increased.

The Copperhead came up in an exchange between McCurdy and Richard D. DeLauer, the Pentagon's top weapons developer, at a subcommittee hearing Friday.

"I don't think it is going to be in the budget long," McCurdy said.

"Well, we propose, you dispose, Mr. Congressman," DeLauer responded. "We haven't decided whether we want to build it at all."

Earlier, in a letter March 4 to Capitol Hill, Army Secretary John O. Marsh Jr. disclosed that the Army is making a "comprehensive program review" of Copperhead and its "interrelationship with other antitank systems." The program was put in "turmoil" by "drastic restructuring," he wrote.

DeLauer used plainer language in the hearing. "On Copperhead, what we did is stop the production until we get the thing fixed," he testified.

A Martin Marietta spokesman said yesterday that costs per shell have risen primarily because of a sharp drop in the number of shells the government expects to buy. "Martin Marietta's cost performance is absolutely under control," the spokesman said.

The Army aired the new cost figures, which were adjusted for inflation, in the first reports made to Congress under a new law requiring the armed services to reveal any increase of 15 percent or more in the unit cost of a major weapon program. McCurdy sponsored the requirement, joined by Sen. Sam Nunn (D-Ga.), over strong resistance from Pentagon leaders.

Defense Department Comptroller Vincent Puritano acknowledged to the subcommittee at a hearing Friday that the unit-cost reporting requirement "has had the intended effect of focusing senior DOD management attention on specific programs," but contended that it has been "inefficient in other ways."

For an example, he went back to February 1982, when 18 programs exceeded the 15 percent threshold. Yet "true cost growth" was the reason in only five cases, he said. "The remainder breached as a result of program cancellations, increased quantities in the out-years, and congressional reductions."

In a sweeping claim of improved cost efficiency, Puritano said that in the final quarter of 1982, the combined estimated costs of 53 major weapon systems fell about $17 billion. He attributed the decrease--the first in a final quarter decrease since 1973--largely to improvements in inflation.

The Army had justified the original $1.24 billion cost of the Copperhead program with a promise of great accuracy--a 90 percent kill ratio. Shells from initial production runs in 1979, however, scored under 80 percent.

Efforts to improve accuracy increased costs, and the Army lowered its procurement sights. As of Dec. 31, 1981, it planned to buy only 34 percent as many shells, or 44,986, at a unit cost more than three times as high, $30,321. But the inflation-adjusted total cost increased by $12 million, to $1.36 billion.

In the letter to Congress, Marsh said that the program as defined in the president's 1984 budget assumed a procurement of 10,320 shells, at an estimated average cost of $65,806 and an estimated total tab of $673.2 million. "The substantial unit-cost increase is the direct result of the reduced program quantity . . . and the low funding level for" the fiscal year 1983-84 program, he wrote.

The president's 1984 budget called for the Army to spend $45 million for 800 Copperheads in fiscal 1983 and $75 million for 1,415 in 1984, and for the Marine Corps to spend $194 million for an unspecified number of shells in 1984.

After the budget went to Capitol Hill, however, the Army found the 1983 and 1984 Copperhead programs "to be unexecutable because the budget timing assumptions, for the approval of the FY 83 Copperhead program, were too optimistic," Marsh said in explaining the basis for the current review.

The other weapon programs with estimated unit-cost increases exceeding 15 percent in calendar 1982 were: Navy--LAMPS MK III helicopter, 28.8 percent; HARM missile, 20 percent, and Tomahawk cruise missile, 75.3 percent; Air Force missiles--Sparrow, 27 1/2 percent; Maverick, 21 1/2 percent; HARM, 31.6 percent, and ALCM (air-launched cruise missile), 51 1/2 percent.