Depends on the specifics of the one you have.
I spoke with a representative of Browning yesterday afternoon... I only asked about the .30-06 version, and apparently only 305 were scheduled to be made in that caliber.
Information not in the public domain.
Browning introduced the B78 rifle with an octagon barrel in 1972. This model was part of a series of single-shot rifles designed for precision shooting and hunting. The B78 gained popularity for its classic design and craftsmanship.
Octagan
Yes
Browning Automatic Rilfe
Yes
Japan
Embellishment
Besides a number of books published on Browning, and some of the gun collector forums (google Browning collectors) you might start with Browning. They have a website, and are still in business making very nice rifles, shotguns, and pistols.
As far as I know browning did not have any firearms made for them in australia.
Rifles can be purchased from the manufacturers such as Browning or Smith & Wesson. Rifles can also be purchased from third-party stores such as Amazon.