When I loosen the tailcap slightly, it won't turn on. If you need your light to be 'tactical', and always should turn on, I suggest a light that has no anodized threads at the tail.In October of 2012, I sent 5 suggestions to ThruNite to improve the Scorpion, and incorporate into the V3 (which I now understand was changed to Lynx).
The following was my first and most important suggestion:
"1. I have noticed that when I pocket-carry the light, sometimes when I take it out to use it, it will NOT turn on. For tactical purposes this could be dangerous. I've found that if the end cap (where you put the batteries in) is just a few degrees turned-loose then the light will NOT turn on. I have to ensure that the end cap piece is fully tightened down or else the light fails on me upon deployment. Even 3 or 4 degrees of loose-twist from snug will cause the light to become deactivated. I would recommend at least a quarter-turn (90 degrees) before the light cuts out... if possible even more."
Any one know if they have fixed this issue with the Lynx?
But it does take some force, to loosen the tailcap on my sample.