Take care that you don't attribute too much information about a gun to the maker's name. For example, Pape sold both "best" quality grade guns and guns of very ordinary (by Brit standards) quality grade. He, like all gunmakers, had to sell what his customers were willing and had the money to buy. So, the name "Pape" on a gun doesn't tell you anything definitive about the guns quality grade.
To arrive at a basic valuation, you have to consider the Brand Value level of the maker's name, the Original Quality grade of the individual gun, and the Current Condition level. If you are interested in some information on valuing Brit guns, PM me an email address and I'll send you a set of Excel (if you don't run Excel, send a land address and I'll send hard copy).
