QF 4-inch naval gun Mk XIX
| Ordnance QF 4 inch gun Mk XIX | |
|---|---|
Crew of HMAS Cowra at gun drill, Tarakan Island, June 1945  | |
| Type | Dual-purpose gun | 
| Service history | |
| In service | 1939 | 
| Used by |  Royal Navy Royal Canadian Navy Royal Australian Navy  | 
| Wars | World War II | 
| Production history | |
| Designed | 1938 | 
| No. built | 2,023 | 
| Specifications | |
| Barrel length | 160 inches (4.064 m) bore (40 calibres) | 
| Shell | Fixed QF HE, Starshell | 
| Shell weight | 35 pounds (16 kg) | 
| Calibre | 4-inch (101.6 mm) | 
| Breech | horizontal sliding-block | 
| Elevation | -10° to +60° | 
| Muzzle velocity | 396 metres per second (1,300 ft/s) | 
| Maximum firing range | 8,870 metres (9,700 yd) at +40° | 
The QF 4-inch Mk XIX gun was a British low-velocity 4-inch 40-calibre naval gun used to arm small warships such as Bathurst and Castle-class corvette and some River-class frigate in World War II, mainly against submarines.