lonestarbattleship:

Twelve 14"/50 caliber Mark 4 guns for USS California (BB-44) sit at the Mare Island Naval Shipyard, ready to be installed. These guns were rebuilds of earlier 14 inch guns which had suffered from construction defects including drooping and poor accuracy. The rebuilding led to each gun gaining 20 tons of weight and being far stronger than before. Plus, the modifications to the shell chamber led to accuracy improvement.

Photographed prior to 1921.

Note: The shed-like structure may be to protect the breech mechanism. The barrel was just over 18 metres long and weighed 80 metric tons.

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Not the first time Mare Island had to rebuild another shipyards sub-standard work.

lone-star-battleship:

USS Ohio (BB-12) at Mare Island Naval Shipyard, August 10, 1915.

From left to Right of ships in the background: “Intrepid (Receiving ship Mare Island and Out of Commission), USS Cheyenne (Submarine Tender), USS H-1 (SS-28), USS H-2 (SS-29) are just visible along side), New York State Nautical School Ship Newport (PG-12) (Rear of dry dock), and USS Raleigh (CL-7) (Far right at the pier).

Colorized Source

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Dry Dock Number 1.