Familiar mock up?
Looks rather like the FN FAL (Lewis Gun mock-up) from King Solomon's Mines (1985) without the barrel sleeve Foofbun (talk) 17:32, 19 May 2017 (EDT)
Dogati firing the fake Lewis Gun. Note the magazine inserted at the bottom which is a dead give-away the gun is not a genuine Lewis Gun. The movie armourers also fitted a Lewis style rear sight.