that is odd when I tried my buddys tn31 vs my k40 it was nothing like that, they was hardly a difference, either my k40 is putting out more then yours or his tn31 was weaker
Since the K40 has smaller/shallower reflector, and lower price, looking at the hardly-noticeable difference in the pics, I would say the K40 wins overall.
TN31 reflector depth and shape is so much optimized for throw. I don’t think K40 with smaller reflector will out throw TN31.
These pictures are nice beamshots. But for flash lights being very close in performance, we need closer look at the hotspot to know who is winner.
Do one beam shots with someone at far(100-200m) pointing at a white wall and someone stand close to the white wall and take picture of it. Or if you have one long lens to help you. If really want to know who is the winner for sure. By judging a remote hot spot with such close throw performance, it will be very subjective and rely on LED tint. Of course, I believe TN31 out throw K40 unless someone proves me wrong.
Just my suggestion.