Bentaz, the red coloured steel bunnings toolbox is the most convenient, top handle lets you pick it up and easily transport locked out to the hunt or range

but more than necessary by the requirements of the law;
Firearm Act 1996 - SCHEDULE 4 - STORAGE REQUIREMENTS
1 Longarm licences for category A and B longarms
.....
3 Any cartridge ammunition for the firearm must be stored in a
locked container separate from the receptacle in which the firearm must be stored.[/i]
Thats it

so a plastic 100round ammo case with padlock tabs or similar would comply....even if you storage the case on an open shelf...
Varmtr, its called dis-info, either from ignorance or just deceptive behavior / advice....and its really not acceptable from the law-enforcers...it means you CAN NOT rely on their word
Vic Firearms act defines most term used in firearm law including AMMUNITION.....;
From the FA ACT, definitions, always at the start of the text;
cartridge ammunition means ammunition having a bullet or other projectile and a priming device fixed to or enclosed in a cartridge case which is composed wholly or partly of material other than paper;
So if it can not go bang with a bullet IT IS NOT AMMO (I understand in NSW, probably a couple of other ass-backward states, empties ARE classified ammunition

)
Yes, firearm storage is with a not easily penetrable hardwood or steel receptacle, but I personally consider the storage is more to protect YOUR property than pass an inspection... SO if its really secure and made of HW, and you're happy storing YOUR property in it, then go for it!
POWDER may NOT be stored in steel, thats the DG law, enforced by Worksafe and not the police,
Dangerous Goods (Explosives) Regulations 2011(VIC);
69 Explosives not to be stored in safes or refrigerators A person who stores any explosives, except explosives of Classification Code 1.4S, must not store the explosives in a document safe, money safe or refrigerator.70 Storage of Hazard Division 1.1, 1.2, 1.3
(propellant is 1.3C), 1.5 or 1.6 explosives
(1) A person who stores explosives of Hazard Division 1.1, 1.2, 1.3, 1.5 or 1.6 must—
(a) store the explosives in—
(i) a receptacle that complies with regulation 73; and
(ii) a building that complies with regulation 63(1)(b); and
(b) ensure that—
(i) explosives of more than one Compatibility Group are not stored in the same receptacle; and
(ii) detonators, capped fuses and other explosives of Classification Code 1.1B are not stored in the same receptacle as any other type of explosive.
73 Requirements for construction of receptacles A receptacle used for the storage of explosives must be constructed and maintained as follows—
(a) the construction of the receptacle must be sturdy; and
(b) the receptacle must have a close fitting closure; and
(c) the inner construction of the receptacle must—
(i) be made from, or be lined with, plywood or close joined timber or another suitable non-sparking material;
and
(ii) not include exposed iron or steel.
To reiterate, storage of propellant (and primers) is covered by the Dangerous Good (explosives) laws not the Firearms Act....