This gun is a further iteration on the ultra short 5.56mm M16K carbine made by La France. The M16K-45 uses proprietary upper and lower assemblies resized for the smaller cartridge, as well as using La France’s patented adjustable twin gas tube system, designed for higher reliability on short barrel guns. It uses M1 Thompson stick magazines.
Looks like something someone made in their garage from leftover parts.
The upper receiver is definitely all made by La France. The boxy Fisher-Price looking carry handle is quite distinct. All sources say the lower is also proprietary, but I’m pretty sure they at least started with an existing 80% lower and modified it given how standard all the fine details look, and how drastically different the machining is to the upper.