I'm new to bowhunting and was curious as to why a compound bow will blow it's cams if you fire it with no arrow? From what I can see, the arrow and head place little weight on the strings. Also, I have seen videos of guys shooting down from a treestand and having their bows blow up in their hands. Is it because of a cheap bow? Or is shooting down the same as dry firing?
Others will be able to expand far beyond what I can, but Compound bows hold a high amount of energy at full draw. That energy has to go somewhere, and that is usually the arrow. When dry fired, the energy has no place to go except up the string. The Cams are the first and weakest point that the energy reaches. I wouldn't think that shooting down is the same as dry firing, because your bow certainly has more force than gravity. If your arrow set up is already on the light side, it could be enough to make a bow malfunction. Now, many bows made today are very tough. Yes, you never want to purposely dry-fire your bow, but I know many will survive a few. My wife accidentally dry-fired her Drenalin last year. We took it inside, and gave it a very thorough check-over (cams, bolts, accessories...). The only thing that moved was her peep. Lucky!
Here's a quick video to show all the energy in a compound. http://www.youtube.com/watch?v=jGo4FJ53nGI&feature=related Now imagine adding all the arrows energy to that little string!
Shooting down out of a treestand had nothing to do with whatever bows you saw blow up. Fitz hit it pretty well. The cams aren't the only thing that a dry fire can effect. They can cause the string/cables to jump the tracks, cams to warp, axles to bend, limbs to crack/split, risers to bend, limb bolts to shear or bend; it's just not something you want to have happen. That arrow needs to be on the string in order to absorb the energy from the bow and it needs to weigh at least 5 grains per pound of draw weight in order absorb enough energy not to void the warranty on most bows.
