I could never quite figure the "Value" of a vent rib on a field gun. Just a place to gather debris & moisture should you get caught in a rain etc. I think the addition of the V-rib would be my cut-off point for buying a model B, unless it was Extremely cheap, as in paying me to take it.
As Larry said the earlier B's were better guns, all they really needed was a little more atention to detail, rather than adding Freu-Frau. Even so an early B with slim forend, two triggers & extractors is not a bad field gun & as I recall they all did have walnut stocks, even if rather plain wood.
