This is an interesting theory about reuse of the 9cm Kanone 1861.While reading your article I could not help but think about a comment made by a Turkish Navy EOD Officer I worked with in Bosnia.To paraphrase his statement--- we cannot always order new equipment, we more than you, reuse old equipment in ways that was never originally intended.
By the way, I remember seeing a barrel for a 9cm K. "61 at the Turkish Navy Museum in Istanbul. I do not recall if it had rifling.
Osman Levend over at the Axis history forum, whose father was an artillery officer in the War of Independence, made the comment the old Imperial Arsenal was noted for piecing guns together from bits and pieces.
I'm not certain the barrels were from C61s, there were Naval guns similar in size and appearance to the Army gun. The South Australian website www.tributesofhonour.org says the gun at Quorn is a naval gun. It's a bit difficult to examine the Quorn gun - 3 hour flight + 4 hour drive.