Con:
My understanding was that Geoff McD_ had one, Dave M_ also (now sold?), this one in Darwin belonging to Chris G_, and one in Africa. You may be able to correct my assumptions...

Not sure of the origins of Chris's rifle. Will ask about provenance and take a photo or two when I see it next.

We Aussies obviously respect our bowling-balls a bit more than our American friends. Now, pins are a different matter....!