Now hittin a half inch turtle head at 50 yards is about the same as hitting a man sized target at 1000 yds, in perfect weather conditions, so this ain�t like shootin fish in a barrel.
Now that depends, you targeting center of mass or just head shots at 1k?

Besides there isn't as much wind drift @ 50 Yds.

Good shooting! I did the same thing a few years back, except the distance was about half of yours, and I used my .177 Air Arms TX200.