The Twin 2 pdr Gun was adopted for land service in 1937. The Naval Mark 8 Gun on a modified twin mounting was approved. A design for a new twin mounting more portable than the Navy type was then to proceed. At the same time the 40 mm Bofors was also adopted. As this was soon shown to be much more effective, the adoption of the 2 pdr was rescinded. Fewer than 60 units were made and installed at various ports and base areas in 1938-39. Once there were sufficient Bofors, the 2 pdrs were replaced. In May 1943 they were declared obsolete for land service and transferred to the Navy.
The Twin 2 pdr Gun was automatic, operated by recoil. Although it looked like an oversize machine gun, the mechanism was very different. It used a vertical sliding breech block. The two guns were mounted one above the other. The top gun was fed from the left and the bottom gun from the right. It was fed by flexible belts carrying 14 rounds each. The mounting was static but could be moved by a special ‘Carriage Transporting 2 pdr AA Equipment mark 1’. There were two mountings, the Mark 1 based on the original Navy mounting and the Mark 2. The Mark 2 soon replaced the Mark 1 as it incorporated several small improvements.
Data
2 pdr QF Gun Mark 8 on Mounting Mark 1
| Weight of Gun & Breech Mechanism | 125 lbs |
| Total length | 96 inches |
| Length of bore | 62 inches |
| Rifling | 12 grooves, uniform Right Hand 1/30 |
| Breech Mechanism | Vertical sliding block, automatic, percussion fired |
| Elevation | -10º to +80º |
| Traverse | 360º |
| Recoil | Hydro-spring, constant 7.4 inches |
| Weight in action | 16,688 lbs 7.75 tons |
| Rate of Fire | 60 rounds per minute per gun |
Performance
Firing standard 2 lb HE Shell
| Muzzle Velocity | 2,275 feet per second |
| Maximum horizontal range | 7,500 yards |
| Maximum ceiling | 16,000 feet |
| Effective ceiling | 6,000 feet |
Ammunition
Fixed, case charge
| Shell, 2 pdr HE, HV, Mark 1T | Same shell as Anti-Tank gun. Filled with TNT with Percussion Fuze No. 243. Tracer No. 7 or 10 in base gave self destruct |
| Shell, Semi-Armour Piercing Mark 2C | Cordite in brass or steel case with percussion primer No. 16 |