5-inch/31-caliber gun

The 5"/31 caliber gun (spoken "five-inch-thirty-one-caliber") were used in the secondary batteries of the United States Navy's "New Navy" protected cruiser Chicago and later mounted in Panther during the Spanish–American War.^[1]

5"/31 caliber Mark 1 Naval Gun
Type	Naval gun
Place of origin	United States
Service history
In service	1889–1910
Used by	United States Navy
Wars	Spanish–American War
Production history
Designer	Bureau of Ordnance
Designed	1885
Manufacturer	U.S. Naval Gun Factory
Produced	1885
No. built	2
Variants	Mark 1 Mod 0 and 1
Specifications
Mass	6,190 lb (2,810 kg) (without breech)
Length	159.97 in (4.063 m) Mark 1 Mod 1
Barrel length	153.97 in (3.911 m) bore (31 calibers)
Shell	50 lb (23 kg)
Caliber	5 inches (127 mm)
Traverse	−150° to +150°
Rate of fire	6 rounds per minute
Muzzle velocity	2,300 ft/s (700 m/s)
Maximum firing range	16,000-yard (14,630 m) at 30° elevation

Design

Mark 1, Nos. 1 and 2, were 31 calibers and two of the first steel tube guns that were built entirely in the United States. They were trunnioned guns, no liners and that fired bag ammunition. After the Spanish–American War was over they were modified to Mod 1 in 1901. A liner was inserted in the breech end and the trunnions were cut off. The Mod 1 consisted of tube, jacket, and 9 hoops. After these changes the gun was able to use the same ammunition as the later Mark 2 5-inch gun.^[1][2]

Naval Service

Ship	Gun Installed	Gun Mount
USS Chicago (1885)	Mark 1 Mod 0: 2 × 5"/30 caliber (removed April 1898)	Mark 1: 2 × single mounting with gravity return
USS Panther (1889)	Mark 1 Mod 0: 2 × 5"/30 caliber (installed July 1898)	Unknown