Even with landowner permission it doesnt mean you will be granted a visitors permit. The Firearms Registry told me that they would generally only issue a permit if it was endorsed by an outfitter. 2 reasons - to stop every second landowner acting as an unlicenced outfitter (as they would) and 2. to try to stop too easy access to the permit - an open invitation to FIT hunters to tresspass.

With the outfitters endorsement it is a fairly simply procedure but you do have to get the details 100% correct or you can end up in strife. As some hunters found out last year and are still trying to get their guns off customs!

Once you get your permit - a photo identification it is very easy to get your firearms through Darwin airport and the licence allows you to buy ammunition over the counter but as Nitro pointed out thats not always easy.

Cheers
Matt