Very nice early Ball Gun. It is early, 1884 or so. This is before they did extended top straps. The gun has a charge of 10 drams which is a bunch. I have an 8 Paradox, and that is 8-10 drams. There were more than one damascus 12 made. The serial number of early paradoxes were 11XXX then 15XXX.
I would get 20 Rocky mountain 8 bore cases made with the "H&H 8" embossed as the headstamp, and shoot about bore diameter balls. 69 to 74 grains of Blue dot should set you free...

Mick is a friend of mine. I should of bought that gun 8 years ago!
JZ