Yesthankyou. But HOW? And if you say "with your eyes" I'll beat you with a frozen halibut.

(They don't have a Frozen Halibut smiley)
This rifle is equipped with a rifle grenade launcher on the muzzle and a flip up ladder-type grenade sight mounted just behind the front sight. The grenade sight has three "steps" for various ranges. The sight itself is notched, like the rear sight of the rifle. I'm wondering if this sight is designed to be used as a rear sight when launching grenades. If so, what is used as a front sight? If not, how is this sight used?