Im not pointing anyone out or pulling the he-man card, but i think some of the reason for arrows coming off of the rest is b/c people are overbowed. Yeah shooting out in the backyard most of us can shoot a bunch and feel no pain etc... But its all a different story when you are out in the cold and trying to draw back on a deer... Tuning/string pinch is also a cause of this but i tend to think that it is b/c people are trying to handle more weight than they truly can when the moment comes.
Ive had it happen once that i can remember of, and it was b/c of all things mentioned. I had a big jacket on, was cold, and the deer was close so i was not prepared as to what would happen when i drew the bow.
Just some food for thought, cuz i definately can see that ruining many guys hunts every year...[:'(] Oh... I ended up spooking the deer off as well trying to get my arrow back on the rrest[

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Derek