The Lusa marries some concepts from the HK MP5 and Uzi submachine gun without being too similar to either. The complete trigger housing is nearly identical to that of the MP5, however the other internals are greatly simplified. The bolt and carrier are one welded unit, and the action is a simple blowback, unlike the roller-delay system of the MP5. The Lusa fires from the closed bolt position in both semi- and fully automatic modes. However, the Lusa's barrel can be quickly changed without tools, like the Uzi. The Lusa uses a non reciprocating ambidextrous charging handle with no provision to lock the bolt to the rear, nor does the bolt lock to the rear upon an empty magazine. The rear sight is a simple diopter with screw adjustment. The body is formed from a sheet of stamped and welded steel.