i spent 3 days tracking up a big ol' boar hog only to completely miss him at 40 yards when i finally saw him. the only thing i could figure is i hit an unseen twig or something, checked my gun the next day and i was 2' high. got it lined back up and a week later i finally tracked him up again and missed him clean at 30 yards, no brush. checked my zero next morning and about 2' low and left. figured the scope was bad, turned out the gun shop where i got the scope, rings and base from (ex-employee)only put 1 screw in the scope base.