Based on the grenade sight gas plug, what looks like some baby poo paint on the handguards, and the long buttstock it appears to be a South African contract kit.
I'm not so sure. I think gska might be on to something. The buttstock is definitely longer than any of the 4 Imbel kits that I've built. This is off of an Imbel kit. (I shortened the barrel up to 18")