I do not know about a journal, but I do keep records about guns I bought. When, where, price, family connections if any, known history of the gun. That type of information. I spent many hours trying to get our family photos identified and dated to when they were taken, who is in them and the houses in the background. Sadly many old photos are just family members or people I just can not identify. Too many cousins look alike and many deceased people left few heirs to ask for information.
My guns tell a different story as I have just about a complete history of every family gun in my possession. Many are tied to photos of the previous owners and some show them with the gun in question. A 1911 came back from WWI with one grandfather and a Luger came back from WWII from an uncle. Doubles used by both grandfathers hunting and other guns used by friends and family over the years. I like the family connections and hope to keep them intact for the next generation. What they do with the information I can not predict but I passed it on in good shape for anyone who is interested.