I bought a Summit Cobra last year. I usually put it on at the truck before walking to the stand(anywhere from about a 1/6-3/4 mile walk). The leg straps usually get a little loose, but not much. Everything else stays put. I tighten the leg straps before climbing up the tree, and they stay tight for the rest of the hunt. Maybe you just have to use it a little to get the straps roughed up a little.
If you can' t figure it out, see what Summit says.

peashooter