The De Lisle carbine or De Lisle Commando carbine was a British carbine used during World War II. The primary feature of the De Lisle was its very effective suppressor which made it extremely quiet in action.
Few were made as their use was limited to special military units.
The designer was William De Lisle. It was based on a Short, Magazine, Lee-Enfield Mk III* converted to .45 ACP by modifying the receiver, altering the bolt/bolthead, replacing the barrel with a modified Thompson submachine gun barrel, and using modified magazines from the M1911 pistol. The primary feature of the De Lisle was its extremely effective suppressor, which made it very quiet in action. So quiet, in fact, that working the bolt to chamber the next round makes a louder noise than firing a round. The single-shot, bolt operation offered an advantage in that the shooter could refrain from chambering the next round if absolute silence was required after shooting. A Semi-automatic weapon would not have offered this option as the cycling of the bolt coupled with rearward escaping propellant gas would produce a noise with each shot.
The De Lisle was made in very limited numbers; 129 were produced during the period of 1942 to 1945 in three variations (Ford Dagenham Prototype, Sterling production and one Airborne prototype). Thompson submachine gun barrels were modified to provide the .45 calibre barrel, which was ported to provide a slow release of high pressure gas.
The suppressor, 2 inches (5.1 cm) in diameter, went all the way from the back of the barrel to well beyond the muzzle (the suppressor makes up half the overall length of the rifle), providing a very large volume of space to contain the gases produced by firing. This large volume was one of the keys to the effectiveness of the suppressor. The Lee-Enfield bolt was modified to feed the .45 ACP rounds, and the Lee-Enfield's magazine assembly was replaced with a new assembly that held a modified M1911 magazine. Because the cartridge was subsonic, the carbine was extremely quiet, possibly one of the quietest firearms ever made.
The De Lisle carbine was used by the British Commandos and other special forces during World War II and the Malayan Emergency. It was accurate to 250 metres (820 ft). -- Wikipedia.