Well, it depends on what you will be doing with the rifle. If you are going to be constantly out past 75 yds, then sight in for 50 or 75. The .22 will go out to 300+ yards in a good rifle (bolt action, the semi's suck too much energy). But, I believe, past 120 yards the projectile will have lost too much energy to be effective in a killing situation. But, I have heard reports of plinking at 200, 250, and 300 yards. Don't underestimate the "pip-squeek." If you use it properly, it can be a fun and effective round. Good luck!!
Hueco