These photos are apparently of a Palestinian using some sort of homemade grenade launcher. It looks like it could be a 40mm grenade in the barrel, or maybe some type of 40mm less/non-lethal grenade like round, such as tear gas.
It appears to work by striking the firing pin (a drill bit) with a stone. I would not want to be within 200 yards of somebody firing that weapon.
Russian VOG-25 40mm Grenade. Photo from gunbroker.
Hat Tip: MP.net