I just recently weighed my bike.

Not vintage steel, but my Rivendell Roadeo sits at 20.8 lbs right now and that is with a nitto lugged quill stem and a brooks b17 select; it's also measured ready to ride with two water bottle holders, pedals, saddle ect. I'm sure if I swapped the stem and saddle out for lighter components and put some weight weenie parts on the bike it would go below. I have Rolf Vigor RS wheels on it, Compass 32mm Stampede Pass tires, Shimano 6800 Ultegra components, Nitto handlebar, Nitto seatpost, Tektro brakes and Look Keo Classic pedals.