  The most general supersymmetric model contains baryon number violating terms
of the form $\lm_{ijk}\ \ov{D}_i\ \ov{D}_j\ \ov{U}_k$ in the superpotential. We
reconsider the bounds on these couplings, assuming that lepton number
conservation ensures proton stability. These operators can mediate $n-\ov{n}$
oscillations and double nucleon decay. We show that neutron oscillations do
not, as previously claimed, constrain the $\lm_{dsu}$ coupling; they do provide
a bound on the $\lm_{dbu}$ coupling, which we calculate. We find that the best
bound on $\lm_{dsu}$ arises from double nucleon decay into two kaons. There are
no published limits on this process; experimenters are urged to examine this
nuclear decay mode. Finally, the other couplings can be bounded by the
requirement of perturbative unification.
