Leighton sent a close up of those barrels which are not Stub Twist and which I believe are an early Laminated Steel. In the 1910 9th edition of
The Gun, W.W. Greener referred to "Old-fashioned laminated steel" as being 75% steel, explained the difficulty in coloring.
They might be Stub Damascus or an early Laminated Steel
From the 3rd edition of
The Gun, 1881 "Laminated steel barrels are twisted, and the rods welded in the same manner as the stub Damascus, but the rods are composed of superior metal containing a larger percentage of steel."
More infro here
http://www.picturetrail.com/sfx/album/view/18063717and
http://docs.google.com/Doc?id=dfg2hmx7_52fs85cfgt and
http://docs.google.com/Doc?id=dfg2hmx7_234chsrtv6s 
