5-inch/40-caliber gun

5″/40 caliber Marks 2, 3, and 4 Naval Gun
Brooklyn, gundeck, with 5-inch/40 caliber gun
Type	Naval gun
Place of origin	United States
Service history
In service	1895–1923
Used by	United States Navy
Wars	Spanish–American War
Production history
Designer	Bureau of Ordnance
Designed	1895
Manufacturer	U.S. Naval Gun Factory
No. built	Mark 2: 68 (Nos. 3–70) Mark 3: 119 (Nos. 87–199, 287–292) Mark 4: 16 (Nos. 71–86)
Variants	Mark 2 Mods 0–8, Mark 3 Mods 0–3, Mark 4 Mods 0–4
Specifications
Mass	Mark 2: 7,000 lb (3,200 kg) (without breech) Mark 2: 7,080 lb (3,210 kg) (with breech) Marks 3 and 4: 7,096 lb (3,219 kg) (without breech) Marks 3 and 4: 7,260 lb (3,290 kg) (with breech)
Length	Mark 2:206 in (5,200 mm) Marks 3 and 4:205.83 in (5,228 mm)
Barrel length	200 in (5,100 mm) bore (40 calibers)
Shell	50 lb (23 kg)
Caliber	5 in (127 mm)
Traverse	137° arc (Brooklyn casemates) −150° to +150° (open mounts)
Rate of fire	12 rounds per minute
Muzzle velocity	2,300 ft/s (700 m/s)
Effective firing range	8,500 yd (7,800 m) at 15° elevation
Maximum firing range	16,000 yd (15,000 m) at 30° elevation

The 5″/40 caliber gun (spoken "five-inch-forty-caliber") were used in the secondary batteries of the United States Navy's early battleships, armored cruisers, protected cruisers, unprotected cruisers, and auxiliary cruisers.^[1]