I have to pipe in I guess. I am not disputing the fact that mechanicals are effective on deer. Because I believe that they are. My point is that, even when hunting deer, I want the optimum in penetration. I will always use a fixed for this reason. Kinetic energy IS desolved in the opening the blades. This is the main reason people use the mechanical blades for turkey so that the arrow will not penetrate through. The issue here is how much is enough. Yes the mechanicals are enough to kill a deer but I want to be sure that I have the ulimate in penetration. The pic, that was posted on another forum showed me that I was correct in my thinking. there was alot of extenal damage to the doe on the ground. Obviously there was enough internal damage to kill the deer. The external wound however showed me that there was alot of energy lost ripping the gash in the side of the deer. I personally would like that energy to be pushing through the vitals or bone if it is a marginal shot. I am not taking sides, as I prefer not to. I am just stating my observations and my opinion for what it is worth. Larger cutting diameters and will destroy more area, at the same time will also eat up more energy. It also takes energy to cut a bigger hole ,or to open blades. The smaller the area cut, the less energy needed.Opening blades= KE dissolved. This shows me that this is what I stated. How much is enough. This to me all boils down to proper shot placement and arrow speed. I will not argue that Good mechanicals are effective on deer however I will always beleive that a fixed head will out penetrate a mechanical shot out of the same bow at the same speeds in the same conditions. The mechanicals do have better flight characteristics than do the fixed. Lets face it. There is less suface area to catch the wind. However if the shots are kept within traditional hunting yardages. There won't be enough to make a difference to a skilled archer with properly tuned gear. Everyone has made a good argument one way or the other. But we have to remember that we are all hunting with different gear, shooting at different speeds, wind conditions and are all at different points of our archery career. If the mechanicals work for you, use them. If the fixed work for you ,use them. But lets not keep bringing this up. Just make sure that whatever you choose to use. Put some thought into it first and know your equipment. Make sure that when you release that arrow that you have done all you can do to insure a quick clean kill.