The heaviest weapon the 6th Fallschirmjaegers can field is a Granatawerfer 34, the German 80mm mortar. Ours is based on an original bipod (weighing 40 lbs), the barrel and base plate are unit made reproductions. This muzzle loading piece will fire tennis balls from its PVC plastic barrel using black powder lifting charges ignited by a percussion cap firing system. Deployment of the Granatawerfer is limited to open terrain battles as dense forest areas will block delivery of these light weight rounds to the target.
Our PVC mortar tube will take the pressure of VERY LIGHT LOADS of black powder using only a LOOSE fitting tennis ball. PVC tubes of this type with end-plugs made of wood are used in Fireworks mortars with much larger powder charges to lift heavier shells but they are buried in sand for safety in case one ruptures. I did remote ignition testing and started my loads VERY SMALL and worked them up for maximum range very carefully.
PVC was used because it was easy to work with and for the weight reduction over an 81mm steel tube, but there are other units in the NWHA that use steel for their mortar tubes (they don't have bipods and baseplates). I believe they fire with a pre-made charge that the mortarman lights and drops down the tube and then drops a shell made of plastic pipe fittings about 6" long. There is also a type that uses empty caulking gun cartridges with the tip cut off and the cartridge filled with a little sand and capped with expanding foam, I think these have the lifting charge in them at one end with a fuse.
Our mortar uses loose "F" grain size black powder, this grain size is big enough to drop to the bottom of the tube without getting stuck on the side walls. The charges are pre-measured in flip top containers for different ranges. One reason I use loose powder is that with the original Granatawerfer bipod you can't dump the tube over to shake out any burning debris that you could get with a separate lifting charge. This can be an advantage in that you don't lose your sighting during a quick salvo. The percussion system allows for fast reload time, very similar to the real thing, but has the danger of overheating the plastic tube.
Hammer trip.
There is a metal funnel piece at the bottom of the PVC tube. This funnel was designed to get the powder to drop close to the percussion cap flash hole for positive ignition, and as a way to mount the firing mechanism. It also takes the majority of the blast and ignition heat. The funnel end fits in a cone shaped plastic reducing coupling that takes the inside diameter of the 3 inch PVC tube down to 2 inches.
The funnel was made on the lathe from mild steel, it is threaded to receive the right angle coupler of the precussion cap flash tube. The flash tube is just a bolt drilled through and tapped for the black powder cap nipple, and then is threaded and spot welded into the right-angle coupler in the back of the funnel. The firing mechanism body is machined out of aluminum, the hammer,latch and flash tube is steel. The hammer uses an M16 spring, the latch has an internal coil spring.
The steel powder funnel and firing mechanism fit into the PVC tube.
Our 81mm Mortar started out with a 2" PVC tube inside the 3" as a bore reducer to fire 1 1/4" white plastic pipe caps with a little fused spotting charge in them. But the 2" PVC inside diameter was too tight and the plastic "shell" hung up after a few shots, so I changed it to 3" and switched to tennis balls.
I believe the NWHA Commonwealth Forces use a 2" steel tube with a steel cap on the end for their Knee Mortar. Their shell is also a 1 1/4" white plastic pipe cap but with about 6" of 1 1/4" white plactic pipe glued in it. My understanding is that they use a seperate fused lifting charge. As the inside diameter of the 2" steel tube is slightly larger than the 2" PVC their shells don't hang up as the tube gets dirty. This combo would also probably work well for a US 60mm mortar.
Our Granatawerfer takes a minimun of a three man crew and can be problimatical to set up and use during the fluid combat of a battle reenactment. It does however look very cool and with a bore of 80mm and shell kill radius of 20 feet against infantry, it is one of the biggest toys in town.
