What exactly was the goal - to stop access to .450 caliber bullets that could be used to possibly reload spent military cases? Or to make the posession of the caliber illegal except by military personel so that no rifle that came into the hands of a private citizen could be explained by "I found it on the road" or "I bought it in the market"?

Subjects like this are fascinating, and (to me at least) reinforce the great quote that William Faulkner said about history: "The past isn't dead. It isn't even past."

I also remember, and this may be silly but I'll mention it anyway, a scene in the movie "Quigley Down Under" where the main character is trying to assemble ammunition for his Sharps. He spends the night with a local gunsmith who tells him that his .45 caliber ammunition is illegal (or something to that effect) and Quigley gives him some ideas about how to work around the law.

Is that Hollywood fantasy, or was the caliber likewise illegal in Australia in the late 19th century?