Jim - to get full information you would need to go to H&H who will probably have the history, (at least who bought it), unless built for stock, less likely for one of this quality

With the full serial number info may be in the Paradox book, I am not sure whether it is the heavy load Paradox with the 4 1/2 - 5 dram load (probably given the weight and serial number) or not

Flat hammers were slightly more common on 8 and 10 bores, but certainly were fitted to other bores "best quality" which this certainly is

JVW is correct, it has been completely refurbished and re engraved, (as one would expect if done by H&H)

A very nice example

TH44