I recently acquired a I Hollis mini Snider in 360 rook, It looks similar to yours except not in as nice condition and it shrunk. mine also has an octagonal barrel. Its currently being professionally restored. lovely rifles and I suspect not many around. especially not in the condition of yours. what a treasure. Does anyone know what period I Hollis would have built these rifles? I'm guessing that the introduction of Martini actions both large and small would have spelt the end of Snider manufacture.