Adjacent to each gun and approximately 8 metres below ground, a magazine was constructed to store both shell and cartridges for the guns

• The magazines are accessed by a set of stairs leading from ground level and opening into a short corridor.
  
  Nearby a vertical shaft provides ventilation to the magazine, it is also equipped with a ladder to enable it to be used as an emergency exit.
• The magazines are of massive construction with walls 600mm thick.
•  Ammunition was lowered down into the magazine by means of a davit positioned in one corner of the stairwell. This pic shows the number 3 magazine Shell Store. Note the surviving metal rack framing and the lighting fixtures. The shell hoist up to the emplacement above is at the far end of the Store.

The Burster Slab

• The construction of the 'Burster Slab' is impressive, a layered type of construction forming the roof of the magazine.
• Targets were expected to engage the battery from long range meaning shells would be falling vertically onto the battery (rather than striking the battery horizontally from shorter range). Targets would be described as Destroyers or Cruisers firing 8 inch guns from 25 to 30 kms out in the Gulf.
• The magazines needed to be protected from this plunging fire.
• They were built recessed into the ground using the usual cut and fill method of construction and protection from the plunging fire was provided by the 'Burster Slab'

The Burster Slab layers described

• Refer the design drawing above. Folded steel armour plate froms the immediate ceiling of the magazine (folded or corrugated steel provided the necessary strength). This pic shows the ceiling in the Number 3 Shell Store.
• The armoured plate is covered by a poured slab of concrete nearly 1 meter thick.
• This in turn is covered by 900mm of sand (taken from Pig Bay, the next bay south of Administration Bay).

This is then covered by another slab of concrete 750mm thick - these three layers - concrete then sand then the second layer of concrete - effectively constitutes the 'burster slab' designed to resist the impact of incoming shells falling on the battery/magazines vertically. A second layer of 900mm of sand is laid over the burster slab. A final layer of 0.6 metres of earth completes the installation.

Inside the Magazine
The Magazine Layout

• The three magazines measure 12 x 8 metres from floor to ceiling
• A central wall divides the space into a shell and cartridge store. The first room you step into is the shell casing room or shell store, the room adjacent/behind is where the cartidges were stored. The dividing wall is constructed of brick.
• The shell store is lined with a second skin of brickwork, presumably also in an effort to maintain constant temp/humidity conditions within (see 'Humidity Corridor' below)
• Each of these rooms was previously outfitted with shelving and racks to store the munitions. There is remnant racking along the central wall of the shell store. This is the steel framing upon which the shelving timber planking was constructed.
• Many of the light fittings still remain in place
• The folded/corrugated steel armour plate roof is still in reasonable condition
• The number 1 and 2 underground magazines still have the steel blast doors at the entrance to the shell room.
• Number 1 has a fitted wooden bench still in position outside the entrance to the shell room.
• Unfortunately all Cartridge Rooms show evidence of vandalisation where attempts have been made (some successful) to chip away brickwork to remove solid brass fittings.

The Shell Hoist

• At the end of each magazine closest to the emplacement and leading up to it at an angle was a hand operated hoist. This supplied both shell and cartridge to the working area
• It was in the form of a rectangular metal shaft containing a rotating dredger-like hoist within.
• At each end of the hoist aperture was a series of doors controlled by interlocks to prevent the flash from an explosion passing down to the magazine. If one of the doors was opened, the other would automatically shut.
• The hoist was hand powered
• There is also a vertical shaft ventilation/escape route with an 8 metre steel fitted ladder leading to outside.

Humidity Corridor

• Around the magazine runs a small tunnel or Dry Area.
• This construction was intended to keep the temperature and humidity constant within the magazine as variations could affect the performance of the ammunition