Have you tried to hit something at 300 yards with a mortar, one of the hand guided types without a tripod ? It takes quite a bit of skill and practice.
When I was serving on the Namibian/Angolan border in 1987, it was just 9 guys in my Eng corps unit assigned to about 200 infantry right on an infiltration route.
We got ourselves a device called a "Patmore"
We even learned to fire it from out our armored vehicles which were open on top.
When we did target practice we used to set up close to a local village and then have local villagers select a target for us to hit with smoke mortars. It never took more than 2 shots (about 10 seconds after the first hit) to hit it. Having the locals know that we had and could use such a weapon was probably one of the reasons I am still alive today.