The 66 stock has a lot of flexibility side-to-side. Also, the holes for the cover screws allow movement, so mounting a scope is a study in frustation. I found that, with a scope, I could make shots go off about 2 inches at 25 yards just by resting against the trunk of a tree. The whole series, 10, 11, 12, 66, and 77 work best shot offhand and with open sights. Besides, the rifle is so light that even a small scope seriously affects the balance. That said, I wish I still had one, they were a hoot to carry and shoot.