  Searches for dark photons provide serendipitous discovery potential for other
types of vector particles. We develop a framework for recasting dark photon
searches to obtain constraints on more general theories, which includes a
data-driven method for determining hadronic decay rates. We demonstrate our
approach by deriving constraints on a vector that couples to the $B\!-\!L$
current, a leptophobic $B$ boson that couples directly to baryon number and to
leptons via $B$-$\gamma$ kinetic mixing, and on a vector that mediates a
protophobic force. Our approach can easily be generalized to any massive gauge
boson with vector couplings to the Standard Model fermions, and software to
perform any such recasting is provided at https://gitlab.com/philten/darkcast .
