I would give you a 90 % that this is battery Townsley, Fort Cronkhite, Harbor defenses of San Francisco. From the total lack of camouflage it is post ar prior to 1950. The only other 16 inch battery was Battery Davis and it still retained a distinctive pattern of camouflage paint up to its scrapping. This battery was used by the Coast Artillery School as an instructional/trials battery as late as 1948 and fired the last full caliber 16 inch shots of the US Coast Artillery. Given that the barrel is traversed to the extreme left and the muzzle is uncovered this is probably just prior to its scrapping or prior to maintenance.
Thank you for your answer, ROLAND1369