52 3-pr Hotchkiss QF The 3-pr Hotchkiss was introduced into the British Naval Service (NS) in 1885 to replace the 1-inch Nordenfelt. It was mainly used as auxiliary armament on board Royal Navy vessels for defence against torpedo boat attacks. The British Army in turn adopted it for Land Service (LS) to form part of the armament of forts and coastal defence positions. Although some surviving examples are marked as “3-pr BL” (breech loader) they definitely were QF ordnance. As described under the 1pr, the term quick fire is applied to guns, which are loaded at the breech, but which use a brass cartridge case to carry the charge and to create a gas tight seal. BL on the other hand came to describe guns where the charge was loaded in separate cloth bags and where obturation (gas seal) was achieved by means of a breech mechanism.
The breech mechanism of a Hotchkiss QF gun. Note the pistol grip trigger and actuation crank. The 3-pr was a 47mm, 40 calibre long (40x47mm=1880mm) version of the 1-pr with the same tube and jacket arrangement. It was equipped with the same quick loading vertical sliding wedge breech block and firing hammer design. For Naval Service guns and on naval landing guns (as used by Colonial forces in South Africa) the trigger mechanism consisted of a finger trigger mounted in a brass pistol grip. The 3-pr fired a projectile of 3¼ lb that could penetrate the vitals of a torpedo boat, which were in those days already protected by coalbunkers. Ammunition was fixed and loading was by hand, being made easy by the rigid case. This allowed a trained crew of three men to maintain a rate of around 20 to 30 rounds per minute. The shell cases were either turned or solid drawn. For their naval role the guns were sighted with a ‘speed’ sight on the right-hand side of the breech and a speed fore-sight which fitted into a socket arm on the jacket. The vertical bar of the speed tangent sight was graduated up to 3,400 yards, while the crosshead was marked with a ‘knots an hour’ and a ‘degrees deflection’ scale. On land normal tangent and conical fore-sights were used. Although only sighted to 3,400 yards, the gun had a maximum range of approximately 4,000 yards, but its engagement range against torpedo boats was more in the order of 1,000 yards. Early examples had no recoil control and were mounted on pedestal mountings and later on elastic mountings. Improvements in hydraulics then led to pistons being used to control recoil. On these models the barrel had a piston on either side of the barrel and moved in a cylindrical sleeve, thus doing away with the need for trunnions. A number of guns retained their trunnions and were fitted to