I remembered seeing this one on GB while browsing. This gun has the standard width matted rib (see next paragraph) but it's a gorgeous example cut by one of FN's top engravers at the time. Beautiful work. Looks like it's mint except for the flaws on the stock.
I checked production #'s for 1970 Superposed's in Schwings "The Browning Superposed" and according to his info 617 standard traps were built. Only TWO of those were Midas Grades making this one of the two. A total of 53 Midas Traps were made in 70 - 51 B'ways, 2 standard rib.
No affiliation whatsoever with the seller, just passing it along