THE high-profile battles raging on Capitol Hill over the B-2 bomber and other multi-billion dollar armaments are overshadowing a fight over the proliferation of low-tech weapons that often cost no more than a Saturday matinee: land mines. At issue is legislation that would require the US military to observe a one-year moratorium on using ''antipersonnel'' land mines, except along international borders or in demilitarized zones. Antipersonnel land mines have become a global scourge. An estimated 100 million are strewn in 64 countries, and the number is rising. They lie hidden and lethal for years after the wars during which they are planted, claiming some 26,000 casualties annually, or one every 22 minutes. The vast majority are civilians. The devices also wreak economic havoc. By adopting a one-year ban on the use of land mines designed to injure infantry troops, advocates say, the US would encourage its allies and others to do the same, giving an enormous boost to proposals for an eventual worldwide ban. ''Land mines are the Saturday Night Specials of conflict,'' says the legislation's sponsor, Sen. Patrick Leahy (D) of Vermont. ''Land mines kill far more civilians than all the bombs being dropped and guns being fired.'' Senator Leahy says the timing of his legislation is crucial. Forty-four nations will meet in Vienna on Sept. 23 to tighten the 1980 UN Convention on Conventional Weapons (CCW), which restricts the use of antipersonnel land mines. The administration could ensure the conference's success by adopting his plan, Leahy says. ''Everything I hear from other countries is that they want US leadership and this [Vienna] is the place to do it,'' he says. President Clinton has taken a stand against land-mine proliferation. In 1993, he extended until 1996 a moratorium on US land-mine exports and last year declared his support for an eventual global ban. But for now Mr. Clinton is backing the Army in opposing Leahy's plan. Officials assert that the plan would endanger the safety of US troops. They also argue that it would do little to curb proliferation and the manufacture of mines by other nations, including China, France, and Britain, since few states are prepared to abandon weapons that are easily purchased for as little as $3 a piece. ''Unilateral actions which needlessly place our forces at risk now will not induce good behavior from irresponsible combatants,'' Gen. John Shalikashvilli, chairman of the Joint Chiefs of Staff, said in a letter last week to Rep. Ronald Dellums of California, the ranking Democrat on the House National Security Committee. The letter was sent as part of an intense Pentagon campaign to block Leahy's legislation from inclusion in the compromise version of the 1996 defense budget. The moratorium was overwhelmingly approved on Aug. 4 in the Senate's version but missing in the House bill. The administration says there are better ways to fight the land-mine scourge. One is to curb global sales. Another is to require states to replace conventional land mines with devices that cause them to self-destruct or self-deactivate. Self-destruct mechanisms cause mines to explode within days or weeks of being planted. The US plans to propose in Vienna that the CCW be amended to require signatories to switch to mines that self-destruct within 30 days or self-deactivate within 120 days. Officials say that such a measure would go far toward ending post-conflict civilian casualties and stands a better chance of acceptance than a moratorium. Leahy disagrees. Many people were skeptical an international ban on chemical weapons could be concluded, he says, but 159 states signed one in 1993. Still, Leahy concedes that the Clinton administration will probably prevail. ''I think the administration is loosing a great opportunity to take ... an historic moral position and save far more lives than the billions of dollars we spend on humanitarian missions around the world,'' he says.