  We have searched for neutron-antineutron oscillations using the 5.56 fiducial
kiloton-year exposure of the Soudan 2 iron tracking calorimeter. We require
candidate n-nbar occurrences to have .GE. 4 prongs (tracks and showers) and to
have kinematics compatible with nbar-N annihilation within a nucleus. We
observe five candidate events, with an estimated background from atmospheric
neutrino and cosmic ray induced events of 4.5 \pm 1.2 events. Previous
experiments with smaller exposures observed no candidates, with estimated
background rates similar to this experiment. We set a lifetime lower limit for
oscillation time in iron: T_A(Fe) > 7.2x10^{31} years. The corresponding lower
limit for oscillation of free neutrons is \tau_{n-nbar} > 1.3x10^8 seconds.
