Are there any original earlier Hawken rifles using an English bar/sporting rifle style lock? The only one I know of the the Roosevelt Hawken, which I would guess is a late one.
There's two that use a shotgun style lock I'm aware of, the Atchison and Peterson, but that lock is a bit different than the bar lock. I'm wondering if that type of lock was a little too late to have been used on any J&S period Hawken rifles