If you're on at 100 yds don't worry about an inch or two at 50. A rule I've used for many years is to sight in 3" high at 100 yds, and don't hold over a deer size target clear out to 300 yds. Most people over estimate distance anyway. As for the difference between a 24" barrel and a 22" will not be an issue, as you or an animal wont be able to detect it, probably not over 150 fps. Balistic charts are a good source of information, but only as a guideline. To many things affect a bullet's flight for ballistics to be an exact science, distance above sea level, shooting up or down hill,the temperature at the time you are shooting. The best thing you can do is practice, and find a load you like and stick with it. Different brands of ammo even with the same bullet weight can require a new sightin as they often group quiet differently.