Redoak, As far as I can tell,based on the Scotts I have seen and owned, the difference between the Triplex and the later square X-bolt is the fact that the square X-bolt was machined into the frame and connected to the toplever like a Greener X-bolt,whereas the Triplex top fastener was held into the frame by a plate that was screwed into the top of the frame. The square X-bolt was an immensely stronger design than the Triplex, and easier to fit,also.It also came along when smokeless powder appeared by coincidence.
