...one should always refer to the
original seminal publication as opposed to later editions unless the later editions contain specific new information not in the original.
I've never heard of such a thing, and I have been reading about the American Civil War and guns for 45+ years and have published 30 articles about guns and Civil War collectibles. I've never attempted to locate a first edition vs. a later edition of a book. Indeed, some first editions, such as regimental histories written in the late 1800's can be very expensive, hard to locate, and fragile for constant use and reference.
Now what is common and universally excepted among scholars, both professional and amateur, is that one should try and go to the original source. For example, if The Book of Colt Firearms quotes something from Civil War Guns by William B. Edwards, and Edwards references a report written by Chief of Ordnance J. W. Ripley from the Official Records of the War of the Rebellion (known as the OR), it is always best to go to the OR and read/verify the information for yourself. Of course it depends upon the importance and relevance of the information whether one wishes to pursue the original source or not.
Once again, I have never seen a problem using a later edition of a book as long as the author notes which edition he/she has used.