repair broken hammer

[Colonial Boy]

sorry Colonial but I can't understand your comment

With Rigby’s reputation for really great gun work there is no way that he or his gunsmiths would even consider using a casting for a hammer.
Colt, Remington et al used castings for grip frames and trigger guards but not for hammers.
Of the many hundreds of period hammer blanks that I have examined none were cast, even if only for the fact that it was faster and cheaper to make forgings than castings.