Make sure on the other shots that they aredone in the exact same way as the first such as where the rifle forearm is resting, where your hands are touching the rifle, pulling the trigger the same, etc. Make each shot a carbon copy of the first. Are you by chanceshooting a magnum or hard kicking rifle? You dont notice yourself flinching do you? How heavy is your trigger and how crisp is it? Exactly what type(brand) and caliber of rifle is it. Do you use an ammonia based solvent to remove copper fouling or just plain solvent. What kind of scope is on it. Your problem could be a number of things. Its better to try and eliminate the easier foundproblems before getting in to more technical things likefree floating or bedding of the barrel and action.