Coastguard Battery – The Guns

QF 12-pounder gun from Wikipedia

The QF 12-pounder 12-cwt gun (abbreviated as Q.F. 12-pdr. (12-cwt.) was a common, versatile 3-inch (76.2 mm) calibre naval gun introduced in 1894 and used until the middle of the 20th century.
It was produced by Armstrong Whitworth, Elswick and used on Royal Navy warships, exported to allied countries, and used for land service.

Many guns were mounted on “pedestals” secured to the ground to defend harbours around the UK, and at many ports around the Empire, against possible attack by small fast vessels such as torpedo boats, until the 1950s. There were 103 of these guns (of a total 383 of all types) employed in coast defence around the UK as at April 1918. Many of these were still in service in World War II although they had by then been superseded by more modern types such as twin QF 6 pounder 10 cwt mounts.

A 12-pounder coastal defence gun – at Newhaven Fort

Guns were traversed (moved from side to side) manually by the gun-layer as he stood on the left side with his arm hooked over a shoulder piece as he aimed, while he operated the elevating handwheel with his left hand and grasped the pistol grip with trigger in his right hand.

In British service “12-pounder” was the rounded value of the projectile weight, and “12 cwt (hundredweight)” was the weight of the barrel and breech, to differentiate it from other “12-pounder” guns.

1 pound (usually written 1lb) = 0.45kg, so a shell weighed 12 pounds = 5.44kg

1 cwt (1 hundredweight) = 112 pounds (112 lb) = 50.8 kg, so the barrel and breech weighed 12 cwt = 610kg.

By comparison, the Carlingnose battery had 6-inch guns. The breech and barrel of a 6 inch gun weighed 16,875 lb (7,654 kg) while the shell weighed 100 lb (45 kg). A gun crew could fire 8 rounds per minute – i.e. one round every 7.5 seconds

The crew of a 12-pounder gun could achieve 15 rounds per minute. The smaller gun was easier to manoeuvre to track smaller fast-moving targets like torpedo boats.

The War Office issued this QF Gun Drill manual