The De Lisle Carbine is a WWII era weapon designed for special operations. The De Lisle Carbine chambers the .45 ACP cartridge and fires from a standard 7 round or 11 round 1911 magazine.
The De Lisle carbine or De Lisle Commando carbine was a British firearm used during World War II that was designed with an integrated suppressor. That, combined with its use of subsonic ammunition, made it extremely quiet in action, possibly one of the quietest firearms ever made.
Few were manufactured as their use was limited to specialist military units.
The weapon was designed as a private venture by William Godfray de Lisle (known as Godfray), an engineer who worked for the Air Ministry. He made the first prototype in .22 calibre; this he tested by shooting rabbits and other small game for the table, near his home on the Berkshire Downs.
In 1943, he approached Major Sir Malcolm Campbell of Combined Operations with his prototype; this was informally tested by firing the weapon into the River Thames from the roof of the New Adelphi building in London. This was chosen to discover if people in the street below heard it firing – they did not.
Combined Operations officials were impressed with the weapon and requested De Lisle produce a 9mm version. However, this was a failure. A third prototype, using the .45 ACP cartridge that was favoured by de Lisle, was much more successful. Tests of this showed the weapon had adequate accuracy, produced no visible muzzle flash and was inaudible at a distance of 50 yards (46 m).