Vintage Anti Poachers' Alarm Gun. Pushes into the ground and a cartridge is placed in the barrel. The trap is set such that when an intruder trips a trace line the weight crashes down and activates the cartridge causing a gun shot into the ground. Circa 1900.
All working but would be a bit slow to drop as the rod is no longer smooth. This is quite a tall one of these trip guns so would look quite striking mounted on a wall.