I've been hunting prairie dogs since 1975 and don't seem to have visibly reduced their numbers, but I have learned a few things along the way. I've shot them with probably a dozen cartridges from the .17 Mach IV to the .338, and I think that without question, the best dog load is the .223. It doesn't have the range of the .22/250, and won't produce as many Olga Korbuts and Mary Lou Rettons, but its small powder charge allows you to shoot and shoot and shoot without your barrel getting so hot that you have to stop. Also, before the Great Obama Panic, .223 ammo was cheap, and someday may be again. By the way, the .338 bucks the wind very well, but it spoils too much meat.