Pebble Grain Artillery Boot

[Ron Wood]

Jerry,
The thread on Jan Stills forum by Friedrich M�¼ller "Fritz" on his absolutely mint arty rig seems to support your assessment of the lining being rawhide or at least having the appearance of rawhide. It has that glossy look of dried rawhide. Kind of reminds me of the rawhide on indian artifacts like warclub wrappings or drum heads. Didn't notice any red or blue coloration on Fritz's example though. Could be just the lighting.
I would venture a guess that if it is rawhide, that material was selected for its hardness as Ron Smith suggested, and the fact that it "wears like a pigs nose"...very durable once it has dried. It would stand up well to the constant abrasion of the stock iron and lever. Perhaps that is why you don't see too many boots that are worn through.