My other 45LC rifle is a Miroku Winchester 1873. All the data dictates lower pressure loads for toggle link action rifles. The 1866 is also toggle link, IIRC.
The late RCModel on a pertinent thread: "SAAMI spec for 45 Colt is 14,000 PSI. That is the only pressure suitable for use in any rifle with a toggle-link action."
https://www.thehighroad.org/index.ph...Dlink%20action