ppsh barrel, AK variant shotgun mag, SAW grip, FN/FAL type stock attaching point, mag release and cocking mechanism. No idea where the trigger came from but it will drag something fierce if it even moves back a mm. Appears to be a few old styled SMG parts from a MP40 as well, but then the picture is a little small to see more detail
It is a Sig AMT 510 variant that someone has cut down and added a SAW type grip and a M4 stock to.Lots of machining but straight forward,used to could get parts kits.They were made in 7.5 Swiss,7.62 NATO,7.62x39 and even a couple prototypes in 30.06.That one looks like 7.62x39 cause of the curved mag.
It is pieced togather but still SIG AMT 510 used as basis,reciever,barrel and shroud,hand guard,sights,lower reciever,etc.Lots of machining involved but doable,that picture may be photoshopped but still its an AMT.The are really weird looking guns but very well built.Local guy has a original.