Time evolution in general gauge theories on inner product spaces

After a study of BRST singlets in corresponding reparametrization invariant formulations it is shown that the time evolution of BRST singlets in a BRST quantization of general gauge theories on inner product spaces may be chosen to be determined by a Schroedinger equation. The appropriate Hamiltonian for this is a particular truncated Hamiltonian of the original one. This Hamiltonian leads also to a particular BRST invariant gauge fixed theory. For electromagnetism one gets in this way the gauge fixed theory in the Feynman gauge. This Lagrangian is also shown to be coBRST invariant. (orig.)