Much simpler to deal in Ansley H. Fox doubles where all you have to worry about is KRUPP or CHROMOX.

I was looking at the stock book page for my 16 gauge Grade 2 top action gun and found that it and several others on that page were described as 4 blade Damascus in their barrels. However, serial number 59,361, a zero grade gun described as a PT (plain twist) gun, is also noted as having 4 blade barrels. Only one gun on the page from serial number 54,359 to 54,369, that is described as having Damascus barrels, has anything but 4 blade barrels. I think you will find that 4 blade barrels are more common than we thought, in guns lower than Grade 3. All of the guns, 54,362 to 54,369 are Grade 2 guns and seven out of eight have 4 blade barrels. That doesn't include the 0 Grade PT gun that is also 4 blade. Maybe Chuck would take a look at that order book page and comment.