Originally Posted by
arnrifk
Fred, I previously determined it was an 1868 block by comparing the underside to some photos of both 1868 and 1870 blocks that I was able to find and the fact that the word "Model" was missing from the top. As I stated, I received a copy of Dick Hosmer's book on the 50-70's just the other day and learned for the first time about the thickness issue. I had not known about that before. After looking at the pictures and my rifle, there was no further doubt in my mind. I do not believe the book or any other book I happen to own addresses the issue of interchangability and that's when I decided to ask my question.