10"/40 caliber gun Mark 3

The 10"/40 caliber gun Mark 3 (spoken "ten-inch-forty--caliber") was used for the primary batteries of the United States Navy's last generation of armored cruisers, the. The Mark 3's were the last, and most powerful, 10-inch guns built for the US Navy.

Design of the Mark 3
The Navy's Policy Board call for a variety of large caliber weapons in 1890, with ranges all the way up to 16 in, to use the new smokeless powder that had recently been adopted by the Navy. Because of this new propellant, projectiles could accelerate all the way along the gun barrel, which allowed for barrels of 40, or more, calibers long. This led to the development of the 10-inch/40 caliber gun.

The Mark 3 was specifically designed for the Tennessee-class armored cruisers, numbered in order after the Mark 1 and Mark 2's, Nos. 27–47, with No. 27 being delivered in February 1906. Nos. 27–31, 36, and 45 were all Mod 0's, with Nos. 37–44, 46, and 47 being Mod 1's. The initial Mod 2's were Nos. 32–35, with other later converted to Mod 2. These were all constructed of gun steel. The 10" Mark 3 Mod 0 was built in a length of 40 calibers, had a tube, jacket and four hoops with a locking ring, and a screw box liner, all of which were manufactured out of nickel-steel. The Mark 3 Mod 1's only differed from the Mod 0 in the shape of the front of their chambers and the Mod 2 had a conical nickel-steel liner that was the same length as the tube, with the chamber volume being slightly reduced.