  High-luminosity fixed-target neutrino experiments present a new opportunity
to search for light sub-GeV dark matter and associated new forces. We analyze
the physics reach of these experiments to light leptophobic dark states coupled
to the Standard Model via gauging the $U(1)_B$ baryon current. When the
baryonic vector is light, and can decay to dark matter, we find that the
MiniBooNE experiment in its current beam-dump configuration can extend
sensitivity to the baryonic fine structure constant down to $\alpha_B\sim
10^{-6}$. This is significantly below the existing limits over much of the
sub-GeV mass range currently inaccessible to direct detection experiments.
