Auto-Ordnance, West Hurley Thompson 39 Round “XL” Drum Magazine
The included original instructions tell you to turn it 9 clicks which was crossed out to say 13 clicks. I would recommend starting with far less clicks so you do not overtighten the spring and avoid snapping the rivet that holds the spring in place.
According to www.smallarmsreview.com:
The 39 Round “XL” Drum: In 1975, the Numrich Arms Company of West Hurley, New York began to manufacture their first Model of 1928 .45 caliber Thompson Submachine Guns for the civilian market. They immediately realized that most purchasers of their Thompsons also wanted a classic drum-style magazine to use or display with their guns. To satisfy the needs of their customers they offered a facsimile of the 50-round “L” drum, but the early West Hurley drum only had a 39-round capacity. The drum was reportedly made by altering a drum that was originally designed for a Japanese manufactured blank-firing replica Thompson. The 39-round drum was called the “XL” drum and retailed for $44.50 in 1975. The West Hurley 39-round drum is easily identified due to its lack of markings on the slide plates, and the markings “AUTO-ORDNANCE CORPORATION WEST HURLEY, NEW YORK, U.S.A.” that were placed on the magazine’s cover just under the winding key. While the outside dimensions were similar to an original “L” drum, the internal track and rotor design was quite different from the original manufacture 50-round drum. In 1980 the price of the “XL” drum was increased to $64.95, and production of the “XL” drum was discontinued around 1987.