If the deer was 100yds at a down hill angle than the ballistics would be less than 100yds. If you drew a line straight up (vertical) from where she was standing and straight out (horizontal) from where you were standing the point where they meet is the true ballistic range of the bullet even though it traveling 100yds from exit of barrel to the deer. If you are sighted dead on at 100yds it shouldn't be an issue hitting anything from you on out to that distance. I am more familiar with 50 cal. shooting path though. Have you spent a lot of time learning your gun at different distances? The initial smoke puff can make it hard to tell where you hit also as I'm sure you have noticed.
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