The 6 Pounder Anti-Tank Gun

By 1938 tank armour thickness had increased significantly, British Infantry tanks mounted 60mm of armour at the time and so there was clearly a need for a more powerful gun than the 2 Pounder. Investigation into a 6 Pounder gun was initiated in 1938, initially the requirement was for anti-tank guns but from the start the possibility of mounting the weapon in future AFVs was allowed for. The General staff did not show interest in the project until 1939 when it was realised that tank armour was likely to progress past that of which the 2 Pounder could deal with and so the intention was the ultimate re-equipment of anti-tank regiments with a weapon superior to the 2 Pounder. In January 1940 the Staff accepted the performance of a 6 Pounder (perforation of 70mm) with the proviso that if possible, the range should be something over 500 yards and in April the guns were approved for both tank and anti-tank mounting.

The Ordnance Board was also asked to provide solutions for 80, 90 and 100mm, the board recommended a 20lb shot of 3.45" calibre, the same as the 25pdr but a piece more like the 3.7" AA gun, this requirement was dropped in March 1940.

The 6 Pounder was designed primarily as an anti-tank gun but the tank version only differed in having a lug on the breech ring and the first guns produced were intended to be mounted on tanks. The designers of the A.20 tank intention was to mount a gun heavier than the 2 Pounder, the 6 Pounder was reported in January 1940 to be satisfactory if mounted with a special breech ring, recuperator and with about 2 feet cut off the muzzle, it was intended to mount the gun in the hull of the tank and this was criticised by the Ordinance Board saying that it would be better to design a special gun and the performance loss would make the 2 Pounder just as effective.

After Dunkirk the General Staff would have liked to have seen a more powerful gun than the 6 Pounder but production considerations were paramount, by the end of the year for manufacturing reasons as well as the ease of tank mounting led to the design of a 6 Pounder with a shorter barrel that had approximately the same ballistics. It was also clear that Germany, having experience of 2 Pounders in France would increase their armour and had produced 50mm guns in quantity. At this point in the war Britain's production policy was quantity and not quality and 6 Pounder production interfered with 2 Pounder production, (estimated production rate was 2 6 Pounders for every 3 2 Pounders).

Gradually in 1941 there was a drive first for "6 Pounder tanks at all costs" and then later for 6 Pounder anti-tank equipments, the first tank guns (Mk III) were completed in June with full production commencing at the end of October, the first anti-tank guns (Mk II) were completed in July. Surprisingly unlike most other weapons, carriage production exceeded gun production quite significantly in 1941 with full production commencing in June. Most guns produced in 1941 were the tank version of the gun but it is important to note that they could and were mounted on the anti-tank carriage.

The reduction in barrel length (43 calibre) reduced the muzzle velocity of the gun, this was accepted on the grounds that the guns would normally be in action at short ranges where the loss in performance would be less marked. Action in North Africa in early 1941 had indicated the desirability of increasing muzzle velocity, this was first done by the addition of a cast muzzle break and an increase in propellant charge. Later it was decided to revert back to the 50 calibre piece, these were introduced in August 1942.

6pdr Carriage Data

6pdr Gun Data

• Mk I - Original Gun with L/50 barrel
• Mk II - L/43 version for anti-tank Carriages
• Mk III - L/43 version for tank mounting
• Mk IV - L/50 version for anti-tank
• Mk V - L/50 version for tank mounting

6 Pounder ammunition

Due to two different barrel lengths an thus different muzzle velocities the 6pdr ammunition store is rather complicated. The first type of ammunition was an Armour piercing shot, this was designed at end of 1939/start of 1940. The AP ammunition was over time altered, muzzle velocity was increased with the introduction of increased propellant "supercharge" and the weight of the shot was also increased. Requirements for special penetrative performance led to the request for APCBC in June 1942, the design for this shot was finalised in January 1943 but beforehand a simpler design of APC had been approved in October 1942. In July 1943 design of composite rigid ammunition was called for, the design for this was approved in October 1943. Discarding Sabot ammunition was called for in November 1943 and this was approved in January 1944.

6 Pounder Cartridges

6 Pounder Projectiles

As you can there is a large number different projectiles and cartridges so compiling a full list of penetration figures will probably not be possible. Penetration figures vary from source to source and shot to shot so the following table should only serve as a guide. 

6 Pounder Penetration Table

6 Pounder gun and Carriage production by year (UK only)

6 Pounder ammunition production by year (Filled only), o = overseas imports.

Sources -  6pdr Handbook, Cromwell Handbook, AVIA 46 187, WO 185/178, DEFE 15 180