Just some info that is probably know to some already I'm sure. Browning offered a Monte Carlo Trap stock from the introduction of the guns in '31 until the end of pre-war production in '39. I have owned some and seen several others. A different vent rib was initially offered on the pre-war guns as well. Advertised as the "Non Crossfire" vent rib, it was a low step rib similar in appearance to early low step Perazzi Mirage guns but was un-tapered and @ 3/8" in width,fitted with twin ivory beads. I owned sn # 777 a, 30" trap model choked *&* with this rib and a long tang round knob Monte Carlo stock.I sold it to a good friend in Dallas who was a very active ATA shooter in the 60's & 70's. He still gives it several outings a year in the Flyer rings of Texas and La.All of this stock and rib info is covered and pictured in Ned Schwing's book on the Superposed.