I just picked up my first No4 Spigot grenade launcher and had question on how they were used. I know the cup launchers you fired with the butt on the ground like a small mortar. I have shot many a tennis ball for the kids this way. My question, is this the way the spigots were also fired? Ask this because there is flip up sight with graduations on the spigot launcher. They were not shot from the shoulder??