The "bump" you are feeling is normal. It's when the FP stop forces the hammer down at it's rear travel terminus. I had to get two of my 1911s out of the safe to see/feel what you were talking about.
That slight "bump" is something I've become accustomed to. I had to cycle the slides several times, with the hammer cocked, to re-discover this tactile sensation that I have come to filter out as normal.
This photo shows the uneven application of force to cock the hammer. The witness mark shows what appears to be more force applied to the right side of the hammer. I bet if you inspect the hammer pin you can see this condition causing uneven wear.
I think this condition is caused by the FP stop rocking/rotating in the slide, or, the stop has worn and/or was not machined perpendicular to the slide's vertical plane. If this interface with the hammer isn't square it will induce side-loading on the hammer pin.