Good discussion topic. After bird hunting for almost 50 years, along with trap, skeet, and instructing, I also have a miss here and there. My mistakes are the exact same ones that everyone makes; failing to keep chin on the stock (looking up to see the bird fold), stopping the swing (again, looking to see the bird fall), failing to move feet into shooting stance, and poor gun to shoulder mount. The last two years I have used a tip from another instructor friend; mounting the gun and swinging thru on an imaginary flight path. Vary the flight angle and length of 'flight'. Do this drill 10 or more times before you hunt each day. It is amazing to me how automatic a good tight mount and eye on the bead will become. This little drill will vastly reduce misses, and more importantly, the cripples. Hope this helps.