Sounds tuff as there usually isn't a paper trail with firearms passed down through the family, I tried to find out when my grandpas WWII Colt 45 was assigned, etc and could not find any information besides, this range of serial numbers went to soldiers, this to generals etc. I think the only way your going to be able to trace that one back is by talking to family that have "heard" the history and assuming that what they "heard" was correct.