You will need a Restricted Goods Export Permit (RGP), an Export Declaration (B957), and need to be registered as a client (B319) (only needs to be done once).

The B709 from the Police is for re-importing your firearms and ammunition etc.

Phone your capital cities customs and get them to send to you the forms or go in in person and fill them out there. They need to sight the documents in person and photocopy them. Take enough ID for a 100 point ID test, your firearms licence, details of your firearms and ammo, your firearms registration papers, your airline tickets or itinery of flights.

Some Australia Post branches can also accept the applications once you have had them posted to you.

Customs will only process these documents within 28 days of your date of leaving Australia.

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I understand on the Zim side it is easy to get the correct documentation on arrival. At least that is what I have been TOLD! Need details of which outfitter one is using etc.