SUMMIT TALKS - At the start of the third day of summit talks in his Kremlin office, Gorbachev said that maybe it's "time to bang our fists on the table" to complete work on a U.S.-Soviet treaty slashing long-range nuclear arms stockpiles by 50 percent. "I'll do anything that works," said Reagan, who pressed his human rights campaign at a luncheon with Soviet artists, writers and university students.ARMS PACTS - Reagan and Gorbachev joined the applause as Secretary of State George Shultz and Soviet Foreign Minister Eduard Shevardnadze signed two secondary arms accords. One provides that each superpower will notify the other of the time, place and intended target of intercontinental ballistic missile tests. The other calls for joint tests in each country this summer of devices to measure the force of test explosions.

SIGHTSEEING - After their discussions Tuesday, the two leaders took an unscheduled stroll under heavy security guard through Red Square past Lenin's tomb and through the Kremlin's Cathedral Square, waving and shaking hands with surprised tourists who applauded back. Reagan told one cluster of Soviets that they had decided to "talk to each other rather than about each other, and it's working just fine." Gorbachev told another group that despite their criticisms of each other's countries, "I see that some of this is a misconception . . ."

FIRST LADY - Nancy Reagan, accompanied by the wife of Soviet President Andrei Gromyko, spent the day touring Leningrad and waved to tens of thousands of waving, smiling residents. She marveled at the art treasures of the Hermitage Museum, visited Peter the Great's summer palace and paid homage to the 650,000 Russians who starved in the Nazi siege of World War II.