Very interesting Daryl. The rib is clearly twist, but the brls look like the 'Damascus Higny' or 'Damascus Leclere 3rd quality' illustrated on the Higny poster http://www.littlegun.be/arme%20belge/artisans%20identifies%20h/a%20higny%20gb.htm
Probably a 'One Iron Crolle' variant.
(I'm glad someone other than me has nothing better to do on a long Memorial Day weekend than to 'talk' about guns and damascus barrels )