I have seen rifles develop excessive head space from use. Seems like it is always a hand loader that likes to push the limit. It is metal. It will eventually change shape or wear. I can definitely feel the difference in the action with some of my high mileage guns, but have yet to wear one out.
I have seen a couple 1873 models where the toggle link failed eventually. Both were .357s. I think it is too much cartridge for the design. I would think the 1866 would do the same...eventually.
I haven't worn out a Henry yet, but I don't have one with more than a couple thousand rounds through it.
