After looking at your pictures and reading your comments I went out and tried again. I was trying to hit the shaft towards the spring instead of away from it.
Beyond that I applied more force to the cam shaft and it did come out but with some serious resistance. This breach has not functioned in over 30 years that I know of and who knows how long before that.
The cams and the breach block are still rusted solid in place and I can not see any way to apply adequate force to them if they are stuck as solid as the cam shaft.