The Littlejohn adapter was a squeeze bore attachment for the British 2pdr which fired a 40mm tungsten carbide cored round, which was squeezed down to ~30mm, increasing its velocity.

The APSV Mk.I round had a muzzle velocity of 1280m/s and could penetrate 140mm of armour at point blank range...far higher than standard 2pdr AP. However the tungsten carbide core is susceptible to shattering at high obliquities or against spaced armour, such as the armour on late versions of the Panzer III.

The Mk.II version featured a heavier thicker core and a nose cap, likely to reduce shattering. It also had a ballistic cap added for reduced drag, however these changes reduced close range penetration. This likely made a compromise between 0° penetration and shattering, but due to the ballistic cap it offered improved penetration past 800m.

Interestingly, the Littlejohn was also trialed on 2pdr's fitted to aircraft.

Amazing thumbnail artwork from: Panaristi [ Ссылка ]

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