In conjunction with Armament Research Services, Ian McCollum from Forgotten Weapons made his way into the Royal Armouries to visit a few of the sneaky sentry snipers.
The DeLise took a standard Short-Magazine Lee-Enfield .303 rifle, swapped out a length of barrel from a .45ACP Thompson submachine gun, and feed on a modified M1911 magazine. The magic of the whole thing was that it was integrally suppressed and, due to the subsonic qualities of that round, was very quiet. They even used a method to muffle the bolt-action when it was cycled.
McCollum has a trio of vintage guns including both prototype and Sterling-made production examples to show off, which is rare because there were only about 130 of those critters ever made. Some guys get all the fun.