The spring is inserted in the shaft of the pen, which is the barrel of the mortar and the pen refill iinserted inside the spring. I cut the top of the pen refill so it is a flat surface, which will strike the mortar shell and launch it out of the mortar.
I cut the shaft of the pen to the appropriate length for a mortar in this scale, afixed a baseplate from an old Corps! mortar i had, used support legs from a New Ray mortar i had and painted it up german yellow.
I cut a hole in the base plate so the refill of the pen can slip through it. To fire the mortar i just pull back on the bottom end of the refill, which compresses the spring and then let go.
For a mortar round i used the tips of small syringes i had on hand (a couple of years ago i had to give myself shots in the belly in preparation for a procedure on my heart and being a forward thinking modeller, i kept all the syringes, feeling they'd come in handy one day). The tips are a small thick plastic knob with a needle inserted in the middle and fit perfectly inside my mortar.
I can fire these little mortar rounds about 15 feet distance and they arc about 6 1/2 feet high. I target them at balloons i have inflated. When (if) the mortar round hits the balloon it bursts the balloon in spectacular fashion, nice and ear ringingly loud.
It usually takes several shots to find the range and aim but once i do i get pretty consistent with my shots....just like a real mortar.I just put the finishing touches on an SS mortar crew to go with the mortar.
