We've got the latest 127mm guns for the AWD's, Mk 45 Mod 4's. The problem is that there will only be 3 of them in-service. In any sort of deployment there will be 1 of them at best... The remaining tubes will be ANZAC Class frigates with Mk 45 Mod 2's that are a 30+ year design that haven't improved in firepower, lethality or accuracy in that time. That will be the situation until the late 2030's when the future frigates come into service.
The guns we chose for the ANZAC's in the mid 80's are EXACTLY the same in lethality, range and firepower as the guns on the few ANZAC's that are actually at sea today...
They may a good general purpose gun but they weren't designed to provide sufficient firepower for the type of amphibious operations we seem now to be envisaging. We're going to "unify the littoral domain" and "seemlessly exploit the maritime maneuver space" with these "amphibious assault ships" afterall. Unless anyone objects to us doing so that is, in which case we'll be exploiting the "maritime maneuver space" alright. Exploiting it the hell out of there the way things are going. I can barely imagine the Royal Commission of enquiry we'd have if one of these things actually got sunk...
The current and planned future guns are intended for surface combatants that will be busy fighting the naval battle. How much will a naval commander be willing to place his frigates and destroyers on "the gunline" should there be ANY sort of submarine, surface action or aerial threat whatsoever?
Now if all that isn't sufficient, even the AWD's will still lack ANY sort of PGM and the Mod 4's, despite being an improvement over the Mod 2's remain relatively short-ranged and slow firing. In reality our NGS capability hasn't improved since Vietnam and if anything it's got far worse, given the relative importance of precise guided munitions in every aspect of warfare nowadays, except apparently naval gunnery support...
The best fire support we will be able to provide in support of our amphibious landing will be the 2-4 gun tubes from the deployed naval force, firing un-guided munitions at a rate of about 20 rounds per minute at best.
On top of this, by the RAN's own simulations, we will have 6-8 deployable Tiger ARH's per taskforce. What the sortie rate of Tigers from LHD's will be, is anyone's guess, but this video I think, gives some acknowledgement to RAN's expectations (2x Tigers at any one time...)
Canberra Class - Royal Australian Navy
These short ranged guns with unguided munitions (assuming the ships aren't fighting anyone else) and a pair of Tigers are available to support landings is the best that is planned for at present...
I say this in the full knowledge that our budgetary situation at present won't allow for anything better, but honestly this is a disgrace. We should call a spade a spade for once, instead of calling a spade a bulldozer as we appear to be doing with our amphibious capability...