This gun and I are both very old.

[OH Osthaus]

certainly not a Parkers Brothers shotgun but still a nice piece of family history - i would not use the words "knock off" to describe it,

there was a W Parker who made guns in the UK starting with muzzleloaders- and I see early Birmingham proof marks as well as barrel makers initials. It is hard to be making "knock offs" if you predate the product being copied. people making junk didn't bother to sign their work.

what I see here is a decent - certainly not top - quality gun made for the export market - that was a big part of the Birmingham trade of the 1800's. the 13 tells me the barrel as proofed measure to the 13 guage level- although the chamber will likely be 12's.

I would bet great grandpa laid out what was to him a considerable sum to step up a level from the typical Belgium clunker that saturated the rural shotgun market.

clean and oil it, have a wall plaque made for it and let the future generations know about the man that bought it and fed his family with pride.

and - as to age - hard to pin down - but if you made me guess - 1870's or 80's