The case coloring process used at Utica on their Fox doubles seemed to result in at least two distinct patterns and this gun is one of them. The other is the "mountain ranges" pattern as seen on my Fox-Sterlingworth Wildfowl and my drawbolt gun on the Fox Collectors web site. I've got a 1936 vintage Fox-Sterlingworth (DGJ Volume Fifteen, Issue 3) that shows this style of case colors.
IMHO, and from years of reading Sherman Bell, I'm convinced there must have been some type of bore obstruction to cause this split. My cousins shot early steel shot loads in an old 12-gauge KED-grade Remington Hammerless Double for a few seasons until they bulged the choke and broke the ribs loose, but those old Damascus tubes took the strain!
