The Army, after spending $630 million during six years of development and two years of initial production, has canceled the Copperhead laser-guided artillery shell, according to a Pentagon spokesman.

By ending the program after obligating almost half the funds in the planned $1.3 billion problem-plagued program, the Army will get only 8,000 of the 44,000 high technology shells it originally sought.

The Army's decision was made after the House-Senate conference on the fiscal 1983 defense authorization bill last month cut out further production funds for the Copperhead and approved just $15 million to end the program.

Instead of fighting, the Army decided to accede. "It was a decision on the priority of funds," an Army spokesman said yesterday. The service is facing increased costs on many of its major new programs, and others face reduction or cancellation in the Pentagon's fiscal 1984 budget proposal.

Over the past two years, the Copperhead production shells could not achieve a promised 80 percent chance of hitting a target. At the most recent tests in July and August, an Army spokesman said yesterday, the hit average was 67 percent, which he added was "still pretty good for hitting a target at artillery ranges."

The completed Copperhead shells are to be given the new Rapid Deployment Force, the spokesman said.

The Copperhead was one of several high technology weapons the Army was gambling on to overcome what the service has described as the overwhelming tank threat of the Soviet Union. Designed to be fired by a 155mm. howitzer, the shell has a terminal guidance system which follows a laser path to its target. A laser designator, either directed by a land-based forward observer or by helicopters operators or unmanned remotely piloted vehicles, puts his beam on the target and holds it there so the Copperhead can home in on it.

Using that system, the service hoped to be able to kill almost one tank per shot, and therefore justify the high cost per shell. "Copperhead has a high single-shot kill capability against armored targets," Congress was told by the Army last year, "and is so accurate it can hit moving tanks routinely at 16-kilometer range."

But beginning almost four years ago, some members of Congress began raising questions about Copperhead as the Army began running into reliability problems at the same time that costs kept rising. The problem, according to Pentagon officials, was that once the Copperhead was designed and tested, it was difficult to reproduce an artillery shell that has 12,000 moving parts on an assembly line.

In December, 1979, shortly after the original decision to build Copperhead was made, Secretary of Defense Harold Brown ordered that the production level be held at 200-per-month, rather than 700-per-month the service wanted, until the Army could show that it had achieved an 80 percent hit average with test shells.

This January, Defense Secretary Caspar W. Weinberger announced that the Reagan administration wanted to buy 46 percent more Copperheads than previously planned over the next few years.