I have noticed that 1859 obverse 77's often have hollow areas on the lower part of Victoria's portrait and in the field also. The hollow areas are not consistent in location from coin to coin. I am assuming that there must have been something on the die during striking to cause them. Whatever it was must have moved around. Does anyone have an explanation for the cause?
Here is a photo of a late state obverse 77 with the hollow areas.

Detail of area.
