4.7"/50 Mark 3 (Armstrong)

The 4.7"/50 caliber Armstong gun (spoken "four-point-seven-inch-fifty-caliber") were used in the secondary batteries of the United States Navy's protected cruisers USS New Orleans (CL-22) and USS Albany (CL-23) during the Spanish-American War.

Design
The Mark 3 was a 48.9 calibers built-up gun designed and built in the United Kingdom for use in the two protected cruisers that the US Navy had purched from the United Kingdom before the Spanish-American War. They were based on the British 4.7-inch Gun Mark IV but a non-standard export model, the standard Mark IV was 40 caliber. They were constructed of a tube with a jacket and four hoops that went from the breech to the muzzle. In the US Navy they were referred to as 4.7"/50 Mark 3 Armstrong, or as a "large case" gun, to help distinguish them from the additional earlier "small case" 4.7"/47 Mark 1 and 4.7"/42 Mark 2 guns that had been purchased from Vickers & Sons in the 1890's. Sometime after 1906 two other 4.7" guns were purchased and designated as Mark 4's but no other details survive. By 1924 all of these guns had been "surveyed and condemned" and taken out of service.