The hammer looks to be a crude hand-made replacement. The lock would be "R. Ashmore & Son". as per Mtn Meek from a previous thread...
Howard Blackmore lists Richard Ashmore as "Gunlock maker, Wednesbury, Staffordshire, 1827-55."
It's a typical English import lock of the back action type.
Regarding the patchbox...
It looks like a casting. It was originally made larger, and was shortened to fit this rifle. As cast, it would have probably been intended to be inlet in the center of the buttstock with wood surrounding it. In other words, it wouldn't have been cut to touch the buttplate. It's large enough that I would call it a patchbox and not a capbox.
I'm really digg'n this rifle!