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.
All are "Lightnings". Some are "Broadways" with the optional "Broadway Rib". I've had two, both with factory Monte Carlo Stocks. One had inertia triggers, one had mechanicals. Never saw a Lightning standard rib with 32" barrels. If I found one for sale I'd buy it, maybe.