The 4.7 inch Coast Gun entered service as a naval gun in 1887 and was adopted for land service in the 1890’s. By 1939 the various types and Marks had mostly disappeared leaving just the Marks 3, 3*, 4 and 4*. These were all 40 calibre guns differing only in minor details. The Marks 3 and 3* were built up steel guns and the 4 and 4* were steel and wire.
The breech mechanisms were conical, interrupted-screw blocks operated by a single motion lever. All the 4.7 inch Coast Gun mountings were of a central pivot type which differed only in small details. The largest change was in the Mark 3 which was taller so as to fire from behind a parapet.
Ordnance
| B Mark 3 | Standard gun |
| B Mark 3* | 6 guns issued in 1901 with non-standard breech mechanism. Altered to Mk 3 standard but retained nomenclature |
| B Mark 4 | Steel and wire 1892 |
| B Mark 4* | Slight difference in construction |
Mounting
| Mark 1 | Central pivot, -10º to +20º. Trunnions 45.625 inches above emplacement floor |
| Mark 1* | Mk 1 altered by fitting pistol grip replacing electric firing gear. Sight illumimation added |
| Mark 1** | Converted Naval Mk 2 to approximate Mk 1* |
| Mark 2 | Similar to Mk 1 but trunnions 41.75 inches above floor |
| Mark 3 | Similar to Mk1 but extra high pedastal carrying traverse rack. Trunnions 8 feet 9.625 inches above floor |
| Mark 3* | Mk 3 mounting with Mk 4 cradle |
| Mark 4 | Similar to Mk 2 but -7º to +20º. Larger buffer cylinder. Trunnions 41.25 inches high |
| Mark 5* | Mk 5 mounting (obsolete in 1936) with longer cradle than Mk 4 altered to take Mk 4 gun |
Data
Marks 3 to 4* on Mountings Marks 1 to 4
| Weight of Gun & Breech Mechanism | 4,592 lbs |
| Total Length | 194.1 inches (4,930 cm) |
| Length of Bore | 189 inches (40 calibres) (4,801 cm) |
| Rifling | 20 grooves, straight to 142.685 inches from muzzle then increasing to 1/30 at muzzle |
| Breech mechanism | Interrupted screw, electric & percussion fired |
| Elevation | -10º to +20º Mks 1-3: -7º Mk 4 |
| Traverse | 360º |
| Recoil system | Hydro-spring constant 8 inches |
| Weight in action | Approx. 6 tons with shield |
Performance
| Firing standard 45 lb Semi-AP shell | |
| Muzzle velocity | 2,150 feet per second |
| Maximum Range | 11,800 yards |
Ammunition
| Shell, Semi-Armour Piercing Mark 3 | Semi because it could only deal with lighter armoured craft. Fitted with Base Percussion Fuze No. 501. |
| Propelling charge | 6 lb 4 oz of Cordite in straight taper brass case 15.9 inches long. Fitted with protruding adaptor for taking a Percussion or Electric Tube |