If you're hitting bang on at 50 yards I wouldn't worry about 100 yards. You should be ok. As far as struts comment is concerned he is not 100% correct. A bullet drops immediatedly if and only if the line of site is parallel with the ground. If a person is shooting at 100 yards, the bullet is dropping. But in order to hit accurately the bullet must have been high somwhere in its trajectory otherwise the bullet would have hit low. In order to compenste for this we sight in our guns to allow for the trajectory. The bullet rises then falls again hitting the mark. Most times if you are hiiting dead on at 25 yards you are also hitting on at 125 yards (this is an approximation/example and will depend on caliber/grain to a degree).