The 90mm AMTB Guns
Anti Motorized Torpedo Boat Guns

Technically known as the 90mm M3 fixed mount, the AMTB gun was the fixed mount version of the army’s 90mm anti-aircraft gun. Used in the coast defense roll, the 90mm M3 was supplied with a heavy shield on three sides and remote fire control for use against high speed craft. Due to their speed and great maneuverability, it was feared that these craft could slip past the large coast defense guns and possibly attack the inner harbor.
 
Sixteen guns were deployed around the Los Angeles and Long Beach harbors during world war two at the Gaffey Bulge on the Upper Reservation, Navy Field on the Middle Reservation, at the tip of the Coast Guard base on Terminal Island, and at Bluff Park in Long Beach.
 

Out of hundreds of guns of this type that were built during the war, only a handful of them survive today. In 1992, through the help of the Coast Defense Study Group, the National Parks Service transferred one of the surviving gun mounts with its shield to the Fort MacArthur Museum. The gun is missing from the mount and both the mount and shield have been left exposed to the elements for years. Both pieces will require substantial work to make for a safe and functional exhibit. Volunteers are welcome for this project but to really get started, we need to locate a 90mm barrel from either another AMTB gun or anti-aircraft gun.
 
There is a second mount with a barrel on an Air Force base in Alaska and a third at Fort Monroe, Virginia that belongs to the US Army Casemate Museum. The Fort MacArthur Museum is working with the US Air Force to reach an agreement that would allow us to recover the gun in Alaska. Some of these guns were also shipped to other countries after the war and may still exist in foreign inventories.
 
If you should happen to come across a 90mm gun in your travels, we urge you to contact the museum and let us know were you found it.

90mm AMTB gun without its protective shield in Alaska

The 90mm AMTB mount at Gaffey Street Bulge
 

The 90mm AMTB mount at Gaffey Street Bulge, north.
At one time the City of Los Angeles had mounted a "tourist telescope" here.

The Guns of Fort MacArthur