Anti-IS QF L4 gun and its variants
In order to meet these requirements, the designers had to find a much more powerful gun than the L1A1. The British didn't bother with the small stuff and went right up to a caliber of 7.2 inches (183 mm). Using such a powerful caliber was no accident. This new gun was based on the 183 mm BL 7.2 inch Howitzer, which dates back to WWI. Initially, the howitzer had a barrel length of 22.4 calibers, but this was extended to 33.1 calibers. Unfortunately, even this extension was not enough to fight Soviet tanks.
In 1950, work started on the QF L4 gun, the most powerful tank gun in the world. The gun weighed a little under 4 tons and had nearly 87 tons of recoil force. In order to clear the fighting compartment of propellant fumes, the gun had a fume extractor fitted. Only one type of shell was planned for this gun: HESH (High Explosive Squashed Head). Not only is the caliber of the L4 stunning, but also the weight of the rounds. The propellant was separate from the shell, but this didn't make the loader's job much easier: the mass of the shell was 72 kg, and the mass of the propellant was 32.8 kg.
On November 9th, 1950, the War Office held a meeting to determine what vehicle this super-powerful gun would be placed on. The meeting resulted in four variants:
- A fully armoured fighting machine (effectively a tank) with a fully rotating turret.
- An SPG with powerful front armour, but a limited traverse angle.
- An SPG with a fully rotating turret, but thin armour.
- An SPG without armour.