  We refute a recent claim by Nazaruk that the limits placed on the free--space
neutron--antineutron oscillation time $\tau_{{n\bar n}}$ can be improved by
many orders of magnitude with respect to the estimate $\tau_{{n\bar
n}}>2(T_0/\Gamma)^{1/2}$, where $T_0$ is a measured limit on the annihilation
lifetime of a nucleus and $\Gamma\sim 100$ MeV is a typical antineutron-nucleus
annihilation width.
