When using wire triggers on body grip trap triggers I prefer they should be standing up from the bottom in a V position, with the general exception being diving water sets. I don't think animals like ducking under something any more than I do, but will push through small twigs or grass. Also trigger may occasionally hang up on a jaw, and not completely close, when you have the trap set with the trigger hanging down from the upper jaw. In this situation, when the trap is sprung and closing the trigger falls towards the opposed closing jaw. Whereas if set on a bottom/ground jaw the trigger falls away from the opposed closing jaw and cannot hang up on the trigger.
Another point to consideration is that a trap set close to the bait is much more productive in producing consistent humane strikes, in a box or cubby. This occurs because the animal is stable at the bait and not moving through the trap to get to the bait when the trap is triggered.
Bctomcat, Are you sure a trigger catching a jaw is a top or bottom thing? I am quite sure its caused by the direction the trigger is pushed when the critter sets off the trap, and to a lesser extent the speed of the critter moving and the amount of play int he trigger. The theory is this:
When an animal approaches the trap with the trigger on the side nearest to the animal, it folds the trigger into the trap further, and when the jaw begins moving forward, the trigger follows behind the moving jaw.
If the trigger is on the side of the trap away from the animals approach, the trigger gets pushed out of the trap, and when the trap fires inertia doesn't have time to position the trigger behind the moving trap jaw for a strike. If your trigger wires are at all splayed forward and back, this traps the bar between the two trigger wires further increasing the possibility of a caught trigger. Doesn't happen all the time, but a splayed apart trigger increases the odds of it.
In a blind set, you cant dictate which way an animal goes through a conibear. When in a box, I always put the trap in trigger side out. At worst, it prevents a miss, and at best prevents trigger damage.
Can be tougher to visualize, but I can prove with a video that trigger away from approach is to be avoided for the reason above if a all possible.