Well Fish, this is something that intrigues me, and im for learning as much as I can regarding a swift humane kill.
At this moment in time, my thinking is the trap is set too heavy, so the taupe (as we both know them ) is forcing forward before trap goes off, and the positioning of the trip or whatever, ive picked a few peoples brains on this here and elsewhere and now all my duffus have beeen tweeked, but its all work in progress. Whats traps are you using? & be interested in how the dog is getting on, give us a bell.