QF 4-inch naval gun Mk XIX

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-class corvette and Castle-class corvette and some River-class frigate in World War II, mainly against submarines.

Description
It succeeded the higher-velocity World War I-era BL 4-inch Mk IX (typically deployed on Flower-class corvette s in the escort role). The Mk XIX fired fixed ammunition which was 38.5 in long and weighed 50 lb. The weight of the projectile was increased from 31 lb for the Mk IX to 35 lb for the Mk XIX. The high-angle mounting used for the XIX added some anti-aircraft capability and allowed it to fire starshells to illuminate the battle area at night.

Surviving examples

 * On HMAS Castlemaine at Williamstown, Victoria, Australia.
 * On the parade ground at the Irish Naval Service Base, Haulbowline, Co. Cork, Ireland