Sorry if this posts twice....I tried posting once, and for some reason I can't see it. I've been trying to zero in my rifle (Ruger 308) shooting 150 grain FMJ. I'm shooting a group at 100 yards around 2" high which is where I beleive the bullet should be at that range. However, at 200 yards I am consitantly 4" high. I would expected at two hundred yards to be zeroed. I have two thoughts: 1- I am at an elevation 5,200 feet above sea level. Is this causing the bullet to have less drop than what I am expecting? 2- The targets at the range climb up a gradual slope at 100 yard intervals. The 200 yard target is higher than where I am shooting. Would this effect the point of impact by 4"? Any help would be appreciated. Thanks

Use a ballistics calculator with the info from your rifle, including sight over bore distance, to get a trajectory. Set it up for a 200 yard zero. See how high the ballistics calculator says you should then be at 100 yards. Either zero that much high at 100, or zero dead on at 200, or you can also use the "first zero" (the first crossing point) which will be around 40-50 yards. If the actual bullet behavior does not match the computer, you put something in wrong or have a rifle or technique problem.