'Khyber Pass' percussion pistol

[Patrick Chadwick]

(...which is carried over to the bottom of the barrel, interesting as you can't see it...)
That makes it less likely to be decoration, anf more likely to be structure, i.e. Damascus.

The barrel looks rather like rose-pattern Damascus to me. A careful cleanup is required.

The lock appears to be one of those bits of creative recycling with more-or-less Enfield /EIC lock parts. Only a good cleanup and close hands-on examination can reveal what is original and what is home-brew.