Hi Steve, The gun is a best quality 12 ga. with a wedge forend fastener as you suspected.I also date it to approx. 1871. The barrels are 28" and I suspect they have been shortened from 30". Being pre-choke it doesn't affect performance and the gun seems to balance quite well.Mechanically it is excellent.What impressed me also was a lovely stock that measures 14 7/8" to the original steel buttplate.The original owner must have been a big dude for his time. The gun is totally stripped down at present. I will attach a few more pics with the patent data you requested.
Roy, thank you for the info on Wednesbury, very interesting.





Better to keep your mouth shut and be thought stupid,than open it and confirm.