BillK: Sorry the gun is now scattered round various processes, barrels are good quality damascus and the stock is a replacement with fairly good colour and figure.
Montana: On the basis of the Not For Ball proof marks, between 1875 - 1887. Assuming the Scott patent use number on the action flat is in fact their serial number (it is duplicated in several places internally), 25*** dates to 1879.
Don: At least there is one other out there! Did you get my email about the Form 6's?