My 1959 Browning catalog and price list show the solid rib still being offered on standard weight Grade 1 12- and 20-gauges. The next Browning catalog and price list I have is 1966 and no solid ribs.
Does it state anything about solid ribs being available on Lightenings?
According to Ned Schwing's book on "The Browning Superposed", 1996, page 241, the stock dimensions for the 20 ga were changed in 1960 to D@C = 1 1/2", D@H =2 3/8" from D@C=1 5/8", D@H 2 1/2". The LOP stayed the same at 14 1/4". The post 1960 stock dimensions are much more workable for me than the earlier dimensions with more drop.
Ideally, I'd like to find an all original 1960-1965 Grade I vintage RKLT 20ga Lightening with 28" M/F choked barrels and a solid rib. I am not at all sure it was ever available in that specific configuration. It seems like they may have all been made with vent ribs???