Setting aside the digressions from the original topic I'll make two points.
2. Last time I was there, the NRA Museum had an exhibit on the guns of America's wars. In the Vietnam exhibit they had a Darne, IIRC cut down on both ends. This came with an explanatory card saying the locals liked the Darne-type action because its strength allowed it to close and function, even on paper shells swollen by/in tropical humidity. I'll leave it to the other participants here to hash out the accuracy of the curator's statement.
Dave, the ability of the Darne to function in hot, humid places back in the paper shells day is one reason it came to be. The French had an extensive empire in the 19th century that included a whole lot of hot, humid places.
