The McPherson spring stick deadfall trigger is one of my favorite triggers because of its diversity. It is a very easy trigger to construct and can be used in a variety of traps. In the video below we use it to set a deadfall but it can be modified with a little ingenuity to work for snares or even for pig spears and the like.
The basic design relies on tension vs. round on round, as shown in this illustration. The string connected to the spring stick deadfall is pulling the bait stick towards it, under high tension. The ground peg has a string tied around it tightly that the carved point of the bait stick barely sits in. The two sticks rest against each other round on round making this a very sensitive trigger. The slightest jostling of the bait stick releases the round on round grip and yanks the pointed tip of the bait stick right away from the ground peg releasing, in this case, a heavy rock. The tension from the springstick causes this trap to be very fast and very effective.
Another reason I love the spring stick deadfall trap is because it can be modified to catch any size game. You can catch mice or deer with it depending on how you scale it. One more advantage to this trigger is that it is relatively a safe to set. You set the trigger before you set the trap so you don’t have to try to balance a rock and set the trigger simultaneously. Watch the video below to see this trap in action. And like always, if you have any questions feel free to ask.