i passed up a 20 at a dallas show that asking price was either $225 or $250 and have kicked myself ever since over not buying. i think it may have had a vent rib and was a later one, up in the '70's pressed checkering era. as to blue book, tell the blue book to come up with one at the condition/price stated on lots of guns. particularly having an original IC choke; it's difficult finding good older used guns that's aren't full or at least modified.

roger