SKB, I found a reference regarding the action type, thanks to your triggering of some previously dormant brain cells. The spiral spring action was a Thomas Woodward action, patent 651 of 1876. The action was improved in 1882. Apparently, Adams & Co of London made a lot (relative) guns on that action type. There's about 1/2 a page on the action type in Dig Haddoke's book.