Staff Writer (Updated: 11/27/2012):
After convincing interested authorities of his design, the silenced carbine was formally tested with promising results. Two .22 versions were reviewed though these failed to impress as military weapons. A third form was modified to accept the American .45 ACP pistol cartridge and it was this prototype that ultimately met expectations and put the De Lisle project into motion. The .45 ACP was a rounded-nose bullet perfected through decades of man-stopping scenarios and also featured a low muzzle velocity which, when coupled to a silencer, made for a truly effective silenced weapon. To help extend the range of the .45 ACP pistol cartridge, the De Lisle Carbine made use of a longer barrel which aided accuracy at range to an extent. As such a weapon would be intended for short-range work anyhow, the limiation was negligible. The .45 ACP was also already in circulation within the British war inventory for it was used with stocks of American Thompson submachine guns and Colt M1911 pistols already on hand. A total of 17 De Lisle Carbine prototypes were ultimately produced under the Ford Dagenham brand label and testing occurred in 1943. Prototypes were also tested through active operational use by British commandos in raids along the French coast.
Serial production of De Lisle Carbines was then moved to the Sterling Armaments Company and manufacture spanned 1942 to 1945 with a total of 500 examples on order (a later revision would raise the production request to 600 units). While officially categorized as a "carbine" (a shortened rifle form), the De Lisle Carbine was technically not a carbine nor was it a pistol - it was more or less a "mutt" born of the requirement of war and destined to never fit neatly into any one category. The De Lisle Carbine would join the famous British Welrod pistol and STEN submachine gun in becoming their silenced weapons of the war. It was expected that production would include the full-wooden stock version and a paratrooper version fitting a folding stock (with dedicated pistol grip) for compactness during air drops and general transport.
The De Lisle Carbine design basically consisted of a shortened form of the .303 Lee Enfield No. 1 Mk III (SMLE) service rifle (complete with its bolt-action function) and chambered for the American .45 ACP pistol cartridge. To this was added a large 8.25-inch long silencer assembly encapsulating the metal barrel within. An 8-inch section of wooden forend was added under the silencer to serve the non-shooting hand in support of the weapon. The trigger unit remained mated to the underside of the rifle body in the usual way and the shoulder stock was retained in full. A cleaning kit was contained in a compartment at the base of the stock. The turn-down bolt lever fell against the right side of the gun body as in the SMLE. A short 7- or 11-round detachable box magazine was fitted directly ahead of the trigger unit. A pair of sling swivels were affixed to the underside of the gun - one under the silencer assembly (near the muzzle) and the other under the shoulder stock.
As the De Lisle Carbine retained the Enfield's bolt-action function, the weapon required manual actuation of the bolt-lever to introduce a fresh cartridge into the firing chamber while, at the same time, ejecting a spent cartridge case within (if present). This offered the benefit of complete silence for the shooter where, having fired his initial round, there was no cycling action to be heard. The cycling action did not occur until the operator manually utilized the bolt-lever in the traditional way. As the De Lisle barely produced an audible sound, the cycling action was now the loudest sound generated during firing. A rate-of-fire of approximately 20 to 30 rounds per minute could be reached according to sources. Muzzle velocity was 850 feet per second with a maximum range listed at 400 yards though the weapon remained much more effective within 200 yards of the intended target.
De Lisle Carbine production was based on the availability of outgoing SMLE full-length service rifle stocks within the British Army. Modifications were then made to the receiver and barrel to suit the new role. A dampener was installed for the cocking handle to reduce the mechanical noise being generated during action. The feed was revised to accept Colt M1911 pistol magazines while the chamber were altered to fit the .45 ACP cartridge itself. The internal bolt was shorted several inches while the chamber was lengthened. An ejector port was assigned to the left side of the receiver for ejection of spent shell casings. The silencer assembly was essentially a long black cylinder fabricated of sheet metal and completed with integrated iron sights. Internally there existed a series of discs arranged in an Archimedes-screw-type fashion to help contain the resultant propellant gasses prior to them exiting through ports at the muzzle end following the bullet. This silencer-and-bullet combination did not produce a telltale flash effect at the muzzle which gave the operator a tactical advantage in the dark. All told, the De Lisle Carbine measured a handy 40.5 inches long with a 3.74 kilogram weight (unloaded).
Unfortunately for the De Lisle Carbine, gains made by the Allies in 1944 (spearheaded by the amphibious assaults of northern France and southern Italy) made the 600-strong order of silenced carbines something of a lesser requirement by this time. The need for specially-armed commandos declined as regular infantry and armored forces rapidly moved to contain the Axis gains across the European Theater of War, the critical beachheads now having been secured. This resulted in the cancellation of the original order with only 130 examples having been completed - most being of the solid wooden stock variety. Their disuse in Europe led to their relocation for action in the Pacific Theater where close-quarters combat in the jungle was a regular experience and trusty short-ranged weapons much appreciated. Overall, De Lisle carbines proved their worth in assassinating unsuspecting sentries and senior officers across many fronts of the war - British commandos would claim their fair share of such targets throughout the course of the conflict.
The De Lisle Carbine went on to have something of an extended service life in the post-war years, seeing service in the Malayan Emergency (1948-1960) and the Korean War (1950-1953). Many were ultimately scrapped after the war years to prevent their use in the "wrong" hands, such was the value and utter effectiveness of the silenced De Lisle Carbine. Today (2012), the De Lisle Carbine remains an extremely rare specimen not often encountered in museum collections let alone private hands.