Further to my comment about the photo showing a not so accurate replication:
In the original Delisles, the front of the receiver was bored out, and the barrel extended back. The bolt was shortened dramatically. The magazine housing is up against the front of the trigger guard. This allowed a longer barrel (originals used converted Thompson barrels), and a shorter overall length; larger suppressor. This increases the complexity of the conversion considerably. Using a full length bolt, with the pistol magazine positioned at the front of the receiver is much easier, although not authentic.
Years ago, a member here made a number of very accurate reproductions, having access to the original production drawings; don't know if the photos could be found in the CGN archives.