Greg, there is no standardized way to tell grades. Various makers used various systems at various times. I suggest a study of H&H as they seem to have the most relatively clear cut grades. Basically, you need to learn to recognize gun craftsmanship such as parts fit and finish, engraving coverage and quality, and wood quality. The UK guns are usually very straight forward in matching the base craftsmanship, engraving and wood to the quality. Note that the Original Quality grade (OQ) determined the price and the price set the amount and price of labor that could go into the gun. Best work guns were made by craftsmen capable of best work and paid enough to do it.
