I noticed that the original poster never responded, but I took the question to mean that he's installing a grounding bar to separate the grounds and neutrals, as in a sub-panel.
If this is correct, then naturally, the jumper mentioned first by GF would be contra-indicated.
As an aside, in most cases, a 1/4x20 screw is used to bond a breaker cabinet, and would most certainly be capable of carrying a 50-amp fault current.
